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https://coffeescript.org/v1/

html coffeescript.org collected 2026-10-01 07:22:28 UTC 225,560 bytes, 3,230 lines download raw bytes

1<!DOCTYPE html>
2<html>
3<head>
4<meta http-equiv="content-type" content="text/html;charset=UTF-8" />
5<title>CoffeeScript</title>
6<meta name="viewport" content="width=device-width, initial-scale=1" />
7<link rel="canonical" href="https://coffeescript.org" />
8
9<link rel="apple-touch-icon" sizes="180x180" href="/apple-touch-icon.png">
10<link rel="icon" type="image/png" href="/favicon-32x32.png" sizes="32x32">
11<link rel="icon" type="image/png" href="/favicon-16x16.png" sizes="16x16">
12<link rel="manifest" href="/manifest.json">
13<link rel="mask-icon" href="/safari-pinned-tab.svg" color="#5bbad5">
14<meta name="theme-color" content="#ffffff">
15
16<style>
17body {
18  font-size: 14px;
19  line-height: 21px;
20  color: #333;
21  background: #f6f6f6 url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADIAAAADCAIAAABee8vuAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAB1JREFUeNpi/P79O8PgAyzMzMyD0FlMDIMSAAQYAC22AvZUamhbAAAAAElFTkSuQmCC);
22  font-family: "Helvetica Neue", "Lucida Grande", "Lucida Sans Unicode", Helvetica, Arial, sans-serif !important;
23}
24.container {
25  width: 950px;
26  margin: 0;
27  padding: 80px 0px 50px 50px;
28  clear: both;
29}
30p, li {
31  width: 625px;
32}
33a {
34  color: #191933;
35}
36h1, h2, h3, h4, h5, h6, b.header {
37  color: #000;
38  margin-top: 40px;
39  margin-bottom: 15px;
40  text-shadow: #fff 0 1px 1px;
41}
42h2 {
43  font-size: 18px;
44}
45h3 {
46  font-size: 14px;
47}
48br.clear {
49  height: 0;
50  clear: both;
51}
52ul {
53  padding-left: 20px;
54}
55b.header {
56  display: block;
57}
58li {
59  margin-bottom: 10px;
60}
61table {
62  margin: 16px 0 0 13px; padding: 0;
63}
64  tr, td {
65    margin: 0; padding: 0;
66  }
67    td {
68      padding: 9px 15px 9px 0;
69      vertical-align: top;
70    }
71    th {
72      text-align: left;
73    }
74table.definitions {
75  width: auto;
76  margin: 30px 0;
77  border-left: 5px solid rgba(0,0,0,0.2);;
78}
79  table.definitions td {
80    text-align: center;
81    padding: 5px 20px;
82  }
83blockquote {
84  margin-left: 0;
85  margin-right: 0;
86}
87code, pre, pre > code, textarea {
88  font-family: Monaco, Consolas, "Lucida Console", monospace;
89  font-size: 12px;
90  line-height: 18px;
91  color: #155;
92  white-space: pre-wrap;
93  word-wrap: break-word;
94}
95  p > code, li > code {
96    display: inline-block;
97    background: #fff;
98    border: 1px solid #dedede;
99    padding: 0px 0.2em;
100  }
101  blockquote > pre {
102    margin: 0;
103    border-left: 5px solid rgba(0,0,0,0.2);
104    padding: 3px 0 3px 12px;
105    font-size: 12px;
106  }
107  td code {
108    white-space: nowrap;
109  }
110.timestamp {
111  font-size: 11px;
112  font-weight: normal;
113  text-transform: uppercase;
114}
115.nowrap {
116  white-space: nowrap;
117}
118div.anchor {
119  position: relative;
120  top: -90px;
121  margin: 0 0 -20px;
122}
123div.code {
124  position: relative;
125  background: #fff;
126  border: 1px solid #d8d8d8;
127  -webkit-box-shadow: 0px 0px 4px rgba(0,0,0,0.23);
128  -moz-box-shadow: 0px 0px 4px rgba(0,0,0,0.23);
129  box-shadow: 0px 0px 4px rgba(0,0,0,0.23);
130  zoom: 1;
131}
132  div.code .minibutton {
133    text-transform: none;
134    position: absolute;
135    right: 8px; bottom: 8px;
136  }
137  div.code .load {
138    left: 8px; right: auto;
139  }
140  div.code pre, div.code textarea {
141    float: left;
142    width: 450px;
143    background: #fff;
144    border: 1px dotted #d0d0d0;
145    border-top-width: 0;
146    border-bottom-width: 0;
147    border-right-width: 0;
148    margin: 15px 3px;
149    padding: 0 0 26px 12px;
150  }
151    div.code pre:first-child {
152      border-left: 0;
153    }
154
155#fadeout {
156  z-index: 50;
157  position: fixed;
158  left: 0; top: 0; right: 0;
159  height: 100px;
160  background: -webkit-gradient(linear, left top, left bottom, from(rgba(255, 255, 255, 255)), to(rgba(255, 255, 255, 0)));
161  background: -moz-linear-gradient(top, rgba(255, 255, 255, 255), rgba(255, 255, 255, 0));
162}
163
164#flybar {
165  position: fixed;
166  z-index: 100;
167  height: 50px;
168  min-width: 490px;
169  left: 40px; right: 40px; top: 25px;
170  background: #eee;
171  background: -webkit-gradient(linear, left top, left bottom, from(#f8f8f8), to(#dadada));
172  background: -moz-linear-gradient(top, #f8f8f8, #dadada);
173  border: 1px solid #aaa;
174  border-top: 1px solid #bbb;
175  border-bottom: 1px solid #888;
176  -webkit-border-radius: 3px; -moz-border-radius: 3px; border-radius: 3px;
177  -webkit-box-shadow: 0 3px 5px rgba(0,0,0,0.1);
178  -moz-box-shadow: 0 3px 5px rgba(0,0,0,0.1);
179  box-shadow: 0 3px 5px rgba(0,0,0,0.1);
180}
181  #logo {
182    display: block;
183    outline: none;
184    float: left;
185    width: 242px;
186    margin-left: 10px;
187  }
188    #logo svg {
189      width: 225px;
190      height: 40px;
191      margin: 5px 0 0 3px;
192    }
193    #logo path {
194      fill: #28334C;
195    }
196  .navigation {
197    height: 50px;
198    font-size: 11px;
199    line-height: 50px;
200    text-transform: uppercase;
201    position: relative;
202    float: left;
203    padding: 0 20px;
204    border: 1px solid #aaa;
205    border-top: 0; border-bottom: 0; border-left-width: 0;
206    cursor: pointer;
207  }
208    .navigation.toc {
209      border-left-width: 1px;
210    }
211    .navigation:hover,
212    .navigation.active {
213      background: #eee;
214      background: -webkit-gradient(linear, left top, left bottom, from(#eee), to(#f8f8f8));
215      background: -moz-linear-gradient(top, #eee, #f8f8f8);
216    }
217      .navigation.active {
218        height: 51px;
219        color: #000;
220        background: -webkit-gradient(linear, left top, left bottom, from(#e5e5e5), to(#fff));
221        background: -moz-linear-gradient(top, #e5e5e5, #fff);
222      }
223    .navigation .button {
224      font-weight: bold;
225    }
226      .navigation .button::selection {
227        background: transparent;
228      }
229    .navigation .contents {
230      display: none;
231      position: absolute;
232      background: #fff;
233      opacity: 0.97;
234      top: 51px; left: 0;
235      padding: 5px 0;
236      margin-left: -1px;
237      border: 1px solid #aaa;
238      -webkit-border-radius: 3px; -moz-border-radius: 3px; border-radius: 3px;
239      -webkit-box-shadow: 0 3px 5px rgba(0,0,0,0.2);
240      -moz-box-shadow: 0 3px 5px rgba(0,0,0,0.2);
241      box-shadow: 0 3px 5px rgba(0,0,0,0.2);
242    }
243      .navigation .contents a {
244        display: block;
245        width: 290px;
246        text-transform: none;
247        text-decoration: none;
248        height: 12px;
249        line-height: 12px;
250        padding: 4px 10px;
251        border: 1px solid transparent;
252        border-left: 0; border-right: 0;
253      }
254        .navigation .contents a:hover {
255          border-color: #ddd;
256          background: #eee;
257        }
258      .navigation.active .contents {
259        display: block;
260      }
261      .navigation .contents.menu {
262        z-index: 100;
263        border-top: 0;
264        -webkit-border-top-left-radius: 0; -moz-border-radius-topleft: 0; border-top-left-radius: 0;
265        -webkit-border-top-right-radius: 0; -moz-border-radius-topright: 0; border-top-right-radius: 0;
266      }
267      .navigation .contents.repl_wrapper {
268        padding: 0;
269        position: fixed;
270        width: auto; height: auto;
271        left: 40px; top: 90px; right: 40px; bottom: 30px;
272        background: -webkit-gradient(linear, left top, left bottom, from(#fafafa), to(#eaeaea));
273      }
274        .navigation .repl_bridge {
275          position: absolute;
276          height: 12px;
277          left: -1px; right: -1px;
278          bottom: -14px;
279          border: 1px solid #aaa;
280          z-index: 5;
281          background: #fff;
282          display: none;
283          border-top-color: #fff; border-bottom-color: #fff;
284        }
285          .navigation.active .repl_bridge {
286            display: block;
287          }
288        .navigation .code .minibutton {
289          top: 10px; right: 10px;
290          width: 40px;
291          text-transform: none;
292        }
293          .navigation .code a.minibutton.permalink {
294            top: 38px;
295            display: block;
296          }
297
298.bookmark {
299  display: block;
300  width: 0; height: 0;
301  position: relative;
302  top: -90px;
303}
304
305.navigation .contents.repl_wrapper .code {
306  cursor: text;
307  -webkit-box-shadow: none; -moz-box-shadow: none; box-shadow: none;
308  background: #181a3a url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAOCAYAAAAmL5yKAAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAACZJREFUeNpi/P//PyMDBYCJgULAAsQD64JRL1ApDP6PeoEyABBgAKOyBSJI2bJcAAAAAElFTkSuQmCC);
309  border: 2px solid #555;
310  padding: 0;
311  position: absolute;
312  top: 15px; left: 15px; right: 15px; bottom: 15px;
313}
314  .repl_wrapper .screenshadow {
315    position: absolute;
316    width: 200px; height: 150px;
317    background: url(data:image/png;base64,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318  }
319    .repl_wrapper .screenshadow.tl {
320      top: 0; left: 0;
321      background-position: 0 0;
322    }
323    .repl_wrapper .screenshadow.tr {
324      top: 0; right: 0;
325      background-position: -200px 0;
326    }
327    .repl_wrapper .screenshadow.bl {
328      bottom: 0; left: 0;
329      background-position: 0 -150px;
330    }
331    .repl_wrapper .screenshadow.br {
332      bottom: 0; right: 0;
333      background-position: -200px -150px;
334    }
335
336#repl_source, #repl_results {
337  background: transparent;
338  outline: none;
339  margin: 5px 0 20px;
340  color: #def;
341  -webkit-tab-size: 2;
342  -moz-tab-size: 2;
343  -o-tab-size: 2;
344  tab-size: 2;
345}
346  #repl_results, #repl_source_wrap {
347    width: auto; height: auto;
348    position: absolute;
349    margin-bottom: 0;
350    top: 10px; left: 10px; right: 10px; bottom: 15px;
351  }
352    #repl_results.error {
353      color: red
354    }
355    #repl_source_wrap {
356      margin-left: 5px;
357      width: 47%; right: 50%;
358      float: left;
359    }
360      #repl_source {
361        padding-left: 5px;
362        width: 100%;
363        height: 100%;
364        border: 0;
365        overflow-y: auto;
366        resize: none;
367      }
368    #repl_results_wrap {
369      white-space: pre;
370    }
371      #repl_results {
372        text-transform: none;
373        overflow-y: auto;
374        left: 50%;
375        border-left-color: #555;
376      }
377
378/*----------------------------- Mini Buttons ---------------------------------*/
379.minibutton {
380  cursor: pointer;
381  color: #333;
382  text-shadow: #eee 0 1px 1px;
383  font-weight: bold;
384  font-size: 11px;
385  line-height: 11px;
386  padding: 5px 10px 6px;
387  height: 11px;
388  text-align: center;
389  -webkit-border-radius: 3px; -moz-border-radius: 3px; border-radius: 3px;
390  box-shadow: 0 1px 2px rgba(0,0,0,0.2); -webkit-box-shadow: 0 1px 2px rgba(0,0,0,0.2); -moz-box-shadow: 0 1px 2px rgba(0,0,0,0.2);
391  border: 1px solid #b2b2b2; border-top-color: #c9c9c9; border-bottom-color: #9a9a9a;
392  background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAWCAIAAACOpGH9AAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAACxJREFUeNpifvr0KRMDAwPT////4RjE//fvHxiD+Mjsv3//4uSD2FD1AAEGAHv9O3d7p0bEAAAAAElFTkSuQmCC) repeat-x left top;
393}
394  .minibutton:active {
395    border-color: #aaa;
396    box-shadow: 0 1px 2px #e4e4e4; -webkit-box-shadow: 0 1px 2px #e4e4e4; -moz-box-shadow: 0 1px 2px #e4e4e4;
397  }
398  .minibutton::selection {
399    background: transparent;
400  }
401  .minibutton ::-moz-selection {
402    background: transparent;
403  }
404  .minibutton.ok {
405    color: #fff;
406    background-image: url(data:image/gif;base64,R0lGODlhAQAYALMAADOtbj3BeyqVXDq6dTClZy2gYzKoazu+eDm1cyyaYDaycj7DfAAAAAAAAAAAAAAAACH5BAAAAAAALAAAAAABABgAAAQMcMlJZzgDKWBISUIEADs=);
407    border-color: #4ba47c; border-top-color: #53b388; border-bottom-color: #459671;
408    text-shadow: #aaa 0 -1px 0;
409  }
410  .minibutton.dark {
411    border: 0;
412    color: #fff;
413    box-shadow: none; -webkit-box-shadow: none; -moz-box-shadow: none;
414    background-image: url(data:image/gif;base64,R0lGODlhAQAYAMQAAFZWVn19fW1tbXd3d3FxcWtra1tbW3V1dWVlZWJiYlJSUnx8fF9fX3l5eWlpaXNzc35+fgAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAAAAAAALAAAAAABABgAAAURICSOYrA0w/EQQuEgCWMASggAOw==);
415    text-shadow: none;
416  }
417  .minibutton.error {
418     opacity: 0.5;
419     color: #600;
420     cursor: not-allowed;
421  }
422
423@media (max-width: 820px) {
424  .container {
425    width: auto;
426    padding: 1em;
427  }
428  p, li, table {
429    width: auto;
430  }
431  #fadeout {
432    display: none;
433  }
434  #flybar {
435    position: static;
436    height: auto;
437    min-width: 245px;
438  }
439    #logo {
440      float: none;
441    }
442    .navigation {
443      float: none;
444      border: none;
445    }
446  div.code pre, div.code textarea {
447    border-left: none;
448    border-top-width: 1px;
449    width: auto;
450    float: none;
451    margin: 5px;
452    padding: 10px 5px;
453  }
454    div.code pre:first-child {
455      border-top: none;
456    }
457}
458
459/* Highlight.js syntax highlighting */
460/* http://jmblog.github.com/color-themes-for-google-code-highlightjs */
461/* Forked from http://softwaremaniacs.org/media/soft/highlight/styles/tomorrow.css */
462.tomorrow-comment, pre .comment, pre .title {
463  color: #8e908c;
464}
465
466.tomorrow-red, pre .variable, pre .tag, pre .regexp, pre .ruby .constant, pre .xml .tag .title, pre .xml .pi, pre .xml .doctype, pre .html .doctype, pre .css .id, pre .css .class, pre .css .pseudo {
467  color: #c82829;
468}
469
470.tomorrow-orange, pre .number, pre .preprocessor, pre .built_in, pre .params, pre .constant {
471  color: #000000;
472}
473
474.tomorrow-yellow, pre .class, pre .ruby .class .title, pre .css .rules .attribute {
475  color: #eab700;
476}
477
478.tomorrow-green, pre .string, pre .value, pre .inheritance, pre .header, pre .ruby .symbol, pre .xml .cdata {
479  color: #718c00;
480}
481
482.tomorrow-aqua, pre .css .hexcolor {
483  color: #3e999f;
484}
485
486.tomorrow-blue, pre .function, pre .function .title, pre .python .decorator, pre .python .title, pre .ruby .function .title, pre .ruby .title .keyword, pre .perl .sub, pre .javascript .title, pre .coffeescript .title {
487  color: #21439C;
488}
489
490.tomorrow-purple, pre .keyword, pre .reserved, pre .javascript .function {
491  color: #FF5600;
492}
493
494pre .subst {
495  color: #A535AE;
496}
497
498pre .literal {
499  color: #A535AE;
500}
501
502pre .property {
503  color: #A535AE;
504}
505
506pre .class .title {
507  color: #21439C;
508}
509
510pre .coffeescript .javascript,
511pre .javascript .xml,
512pre .tex .formula,
513pre .xml .javascript,
514pre .xml .vbscript,
515pre .xml .css,
516pre .xml .cdata {
517  opacity: 0.5;
518}
519
520</style>
521
522</head>
523<body>
524
525<div id="fadeout"></div>
526
527<div id="flybar">
528  <a id="logo" href="#top"><svg xmlns="http://www.w3.org/2000/svg" viewBox="-22 347 566 100">
529	<title>
530		CoffeeScript Logo
531	</title>
532	<path d="M21.7 351.1c.1.6-.2 1.1-1.2 1.6-1.3-.7-4.1-1.1-6.4-.9-2.5.2-4.6 1-4.3 2.7.4 1.7 2.8 2.7 7.1 2.3 10.5-.9 10.4-8 25.8-9.4 12-1.1 18.7 2.6 19.6 7.1.7 3.5-2.2 6.9-10.9 7.6-7.7.7-12.2-1.4-12.6-3.5-.2-1.1.4-2.7 4.1-3.1.4 1.7 2.5 3.5 7.5 3 3.6-.3 6.6-1.6 6.2-3.6-.4-2.1-4.2-3.3-10.2-2.8-12.2 1.1-15.2 7.8-25.6 8.7-7.4.7-13.4-2-14.2-6-.3-1.5-.3-5 7.5-5.7 4-.3 7.2.4 7.6 2zm-39 41.8c-3.4 4.3-4.9 9.3-4.6 14.2.3 4.9 2.7 8.9 6.5 12 4 3.1 8.3 4 13.2 3.1 1.9-.3 4-1.3 5.9-1.9-4 0-7.4-1.3-10.8-4-3.7-2.7-6.2-6.5-6.8-11.1-.9-4.3 0-8.3 2.4-11.8 2.7-3.4 6.2-5.3 10.8-5.9 4.6-.3 8.6.9 12.6 3.7-.9-1.3-2.2-2.2-3.4-3.4-4-2.7-8.3-4-13.6-2.7-4.8 1-8.8 3.5-12.2 7.8zm53.6-23.1c-12.9 0-24.4-1.3-32.7-3.1-8.9-2.2-13.6-4.6-13.6-7.7 0-1.3.6-2.4 2.4-3.7-5.6 2.2-8.6 4-8.6 6.8.3 3.1 5.3 6.2 15.5 8.6 9.6 2.4 21.9 3.7 36.7 3.7 15.1 0 27.1-1.3 36.7-3.7 10.2-2.4 15.1-5.6 15.1-8.6 0-2.2-2.2-4.3-6.2-5.9.9.6 1.6 1.6 1.6 2.7 0 3.1-4.6 5.6-13.9 7.7-8.6 1.9-19.6 3.2-33 3.2zm36.8 8.6c-9.6 2.2-21.9 3.7-36.7 3.7-15.1 0-27.4-1.6-37-3.7-8.6-2.2-13.2-4.6-14.8-7.1 1.6 10.8 5.3 21 10.2 30 3.7 5.6 7.4 10.5 11.1 15.8 1.6 3.1 2.7 6.2 3.4 9.3 2.4 3.4 5.9 5.6 10.2 6.8 5.3 1.9 10.8 2.7 16.4 2.4h.6c5.6.3 11.5-.6 16.9-2.4 4-1.3 7.4-3.4 9.9-6.8h.3c.6-3.1 1.6-6.2 3.1-9.3 3.7-5.3 7.4-10.2 11.1-15.8 4.9-8.9 8.3-19.1 10.2-30-2 2.8-6.6 5.2-14.9 7.1zm106.2 30.1c-4.8 12.1-17.6 16.9-25.9 16.9-13.4 0-19.9-6-19.9-22.3 0-16.5 7.9-47.3 31.7-47.3 8.5 0 15.2 3.3 15.2 12.1 0 4.8-1.8 8.3-6.4 8.3-1.5 0-3.4-.4-5.2-2.4 2.2-1.1 4.2-4.9 4.2-8.3 0-2.9-1.5-5.6-5.6-5.6-10 0-18.9 23.9-18.9 42.4 0 8.3 2.2 14.2 10.9 14.2 7.1 0 13.5-3.4 17.7-9.1l2.2 1.1zm32.9-16.3c.4.2.7.2 1 .2 4.2 0 10.1-2.7 14-5.5l.8 2.4c-3.4 3.7-9.5 6.5-16.1 7.5-1.5 16.8-10.6 27.3-21.7 27.3-8.4 0-14.5-4-14.5-14.4 0-10.5 6.2-32.2 24.9-32.2 7.8.3 11.6 5.3 11.6 14.7zm-7.7 5c-1.9-.5-2.4-2-2.4-3.8 0-2.5 1.2-4.2 2.8-4.9-.2-3.8-1.1-5.3-3.4-5.3-6.5 0-12 16.6-12 25.6 0 6 1.2 7.3 4.6 7.3 4.2.1 8.9-8 10.4-18.9zm-6.6 39.7c0-8.3 7.1-11 15.8-13.6l10.9-51.9c2.7-13 10.6-15.5 16.5-15.5 4.1 0 8 2.2 9.7 5.7 3.6-4.6 8.4-5.7 12.4-5.7 5.6 0 10.8 3.9 10.8 9.8 0 1.5-.1 2.6-.3 3.7h-4.3c.1-.9.2-1.7.2-2.4 0-2.1-1.7-3.1-3.4-3.1-2 0-4.8 1.1-6.2 7.1l-1.7 7.4h9.1l-.8 3.6h-9l-10.3 49.1c-2.7 13-10.6 15.5-16.5 15.5-5.2 0-8.3-2.3-9.8-5.7-3.5 4.6-8.3 5.7-12.3 5.7-5.6.1-10.8-3.8-10.8-9.7zm9.1 1.8c1.9 0 4.2-1.8 5.4-7.1l1.1-5.3c-5.7 2-10.1 4.4-10.1 9.4 
5320 1.2 1.7 3 3.6 3zm21.7 0c1.9 0 4.2-1.8 5.4-7.1l2.2-10.4-9.4 1.8-1.8 8.3c-.5 2.1-1.1 4-1.8 5.6.9 1.3 3 1.8 5.4 1.8zm-1.4-18l9.4-1.7 7.7-36.8h-9l-8.1 38.5zm16.6-56.7c-2 0-4.8 1.1-6.2 7.1l-1.7 7.4h9l2.1-9.5c.2-.7.2-1.3.2-2 .1-2-1.5-3-3.4-3zm37.9 53c7.1 0 11.6-4 16.1-9.2h3.1c-5.2 8.3-12.9 16.8-25 16.8-8.5 0-14.2-4.2-14.2-14.5 0-10.5 5.9-32.3 24.6-32.3 8.1 0 10 4.2 10 8.7 0 10.5-10 18.5-20.9 19.2-.1 1.3-.2 2.5-.2 3.6 0 6.2 2.2 7.7 6.5 7.7zm5.3-34.4c-4.6 0-9.1 9.7-10.9 18.7 7-.5 13.2-7.4 13.2-15 0-2.2-.5-3.7-2.3-3.7zm28.6 33.4c3.4 0 7.8-2.3 10.8-4.8-2 10.4-8.4 13.4-15.8 13.4-8.4 0-14.1-4.2-14.1-14.5 0-10.5 5.9-32.3 24.6-32.3 8.1 0 10 4.2 10 8.7 0 10.6-10 18.5-20.9 19.2-.1.9-.2 2-.2 2.7 0 5.7 2.5 7.6 5.6 7.6zm6.2-33.4c-4.5 0-9.1 10.1-11 18.7 7.1-.4 13.3-7.3 13.3-15 0-2.2-.6-3.7-2.3-3.7zm51.3-6.7c-1.7 0-3-.6-4.2-1.9 2.4-1.5 4.1-4.8 4.1-7.8 0-3.1-1.8-6.1-6.8-6.1s-8.3 2.8-8.3 8.2c0 13.3 20.5 15.2 20.5 34.8 0 15.3-12.3 22.7-25.6 22.7-10.4 0-19.3-4.5-19.3-15.7 0-9.8 7-14.9 13.3-14.9 3.1 0 7.7 1.3 8 6-4.9 0-10.7 2.3-10.7 8.5 0 4.5 2.9 8.7 8.7 8.7 6.1 0 10.6-4.4 10.6-12 0-15.6-18.6-21.1-18.6-34.5 0-9.5 9.3-16.3 21-16.3 4.3 0 14.6.9 14.6 10.9.1 5.5-2.8 9.4-7.3 9.4zm36.2 10.3c0-2.3-.8-3.7-2.5-3.7-5.7 0-11.7 16.6-11.7 26.7 0 6.2 2.2 7.6 6.6 7.6 7.1 0 11.6-4 16.1-9.2h3.1c-5.2 8.3-12.9 16.8-25 16.8-8.5 0-14.2-4.2-14.2-14.5 0-10.6 6-32.3 24.5-32.3 8.1 0 10.1 4.2 10.1 8.3 0 4.4-2.2 6.7-4.8 6.7-1 0-2.1-.4-3.1-1.1.5-1.9.9-3.6.9-5.3zm27.7-7.6l-1.2 5.7c3.1-2.7 6.7-5.7 11-5.7 4.1 0 6.3 3.3 6.3 6.9 0 3.1-2.1 6.7-6.6 6.7-5.1 0-2.5-6-5.3-6-2.7 0-4.4 1.4-6.7 3.4l-7.2 34.6h-13.1l9.6-45.4 13.2-.2zm34.2 0l-6.6 30.9c-.3 1.2-.4 2.1-.4 2.9 0 2.5 1.2 3.3 3.7 3.3 3.5 0 6.9-3.4 8.1-8h3.8c-5.2 14.8-14.2 16.8-19.1 16.8-5.5 0-9.7-3.2-9.7-10.9 0-1.8.3-3.7.7-5.9l6.2-29.2 13.3.1zm-4.1-19.4c4 0 7.2 3.2 7.2 7.2s-3.2 7.1-7.2 7.1-7.1-3.1-7.1-7.1c-.1-4 3.2-7.2 7.1-7.2zm29.1 16l-1.5 6.9c2.6-2.3 6.1-3.9 10.7-3.9 6.2 0 11.1 3.5 11.1 14.4 0 12.2-4.7 32.1-22.3 32.1-4.5 0-6.8-1.6-7.7-3.2l-4.7 22.1-13.7 3.2 15.2-71.5 12.9-.1zm7.8 17c0-7-2.9-7.5-4.5-7.5-2 0-4.5 1.6-6.3 4.4l-5.4 25.5c.4 1 1.4 2.1 3.4 2.1 9.7 0 12.8-15.9 12.8-24.5zm27.8 17.3c-.3 1.1-.5 2.2-.5 3.1 0 1.9.7 3.2 3.1 3.2.7 0 1.7 0 2.4-.3-2.5 7.8-6.6 8.9-9.6 8.9-6.4 0-9.1-4.4-9.1-10.3 0-1.6.2-3.1.6-4.8l5.8-27.2h-3l.7-3.6h3L528 366l13.4-1.9s-1.4 6.2-3.1 14.4h5.5l-.7 3.6h-5.5l-5.7 27.4z"/>
533</svg>
534</a>
535  <div class="navigation toc">
536    <div class="button">
537      Table of Contents
538    </div>
539    <div class="contents menu">
540      <a href="#overview">Overview</a>
541      <a href="#installation">Installation</a>
542      <a href="#usage">Usage</a>
543      <a href="#literate">Literate CoffeeScript</a>
544      <a href="#language">Language Reference</a>
545      <a href="#literals">Literals: Functions, Objects and Arrays</a>
546      <a href="#lexical-scope">Lexical Scoping and Variable Safety</a>
547      <a href="#conditionals">If, Else, Unless, and Conditional Assignment</a>
548      <a href="#splats">Splats…</a>
549      <a href="#loops">Loops and Comprehensions</a>
550      <a href="#slices">Array Slicing and Splicing</a>
551      <a href="#expressions">Everything is an Expression</a>
552      <a href="#operators">Operators and Aliases</a>
553      <a href="#existential-operator">Existential Operator</a>
554      <a href="#classes">Classes, Inheritance, and Super</a>
555      <a href="#destructuring">Destructuring Assignment</a>
556      <a href="#fat-arrow">Bound and Generator Functions</a>
557      <a href="#embedded">Embedded JavaScript</a>
558      <a href="#switch">Switch/When/Else</a>
559      <a href="#try-catch">Try/Catch/Finally</a>
560      <a href="#comparisons">Chained Comparisons</a>
561      <a href="#strings">String Interpolation, Block Strings, and Block Comments</a>
562      <a href="#tagged-template-literals">Tagged Template Literals</a>
563      <a href="#regexes">Block Regular Expressions</a>
564      <a href="#modules">Modules</a>
565      <a href="#cake">Cake, and Cakefiles</a>
566      <a href="#source-maps">Source Maps</a>
567      <a href="#scripts">"text/coffeescript" Script Tags</a>
568      <a href="#resources">Books, Screencasts, Examples and Resources</a>
569      <a href="#changelog">Change Log</a>
570    </div>
571  </div>
572  <div class="navigation try">
573    <div class="button">
574      Try CoffeeScript
575      <div class="repl_bridge"></div>
576    </div>
577    <div class="contents repl_wrapper">
578      <div class="code">
579        <div class="screenshadow tl"></div>
580        <div class="screenshadow tr"></div>
581        <div class="screenshadow bl"></div>
582        <div class="screenshadow br"></div>
583        <div id="repl_source_wrap">
584          <textarea id="repl_source" rows="100" spellcheck="false">alert "Hello CoffeeScript!"</textarea>
585        </div>
586        <div id="repl_results_wrap"><pre id="repl_results"></pre></div>
587        <div class="minibutton dark run" title="Ctrl-Enter">Run</div>
588        <a class="minibutton permalink" id="repl_permalink">Link</a>
589        <br class="clear" />
590      </div>
591    </div>
592  </div>
593  <div class="navigation annotated">
594    <div class="button">
595      Annotated Source
596    </div>
597    <div class="contents menu">
598      <a href="annotated-source/grammar.html">Grammar Rules — src/grammar</a>
599      <a href="annotated-source/lexer.html">Lexing Tokens — src/lexer</a>
600      <a href="annotated-source/rewriter.html">The Rewriter — src/rewriter</a>
601      <a href="annotated-source/nodes.html">The Syntax Tree — src/nodes</a>
602      <a href="annotated-source/scope.html">Lexical Scope — src/scope</a>
603      <a href="annotated-source/helpers.html">Helpers &amp; Utility Functions — src/helpers</a>
604      <a href="annotated-source/coffee-script.html">The CoffeeScript Module — src/coffee-script</a>
605      <a href="annotated-source/cake.html">Cake &amp; Cakefiles — src/cake</a>
606      <a href="annotated-source/command.html">“coffee” Command-Line Utility — src/command</a>
607      <a href="annotated-source/optparse.html">Option Parsing — src/optparse</a>
608      <a href="annotated-source/repl.html">Interactive REPL — src/repl</a>
609      <a href="annotated-source/sourcemap.html">Source Maps — src/sourcemap</a>
610    </div>
611  </div>
612</div>
613
614<div id="top" class="container">
615  <span class="bookmark" id="overview"></span>
616    <p><strong>CoffeeScript is a little language that compiles into JavaScript.</strong> Underneath that awkward Java-esque patina, JavaScript has always had a gorgeous heart. CoffeeScript is an attempt to expose the good parts of JavaScript in a simple way.</p>
617<p>The golden rule of CoffeeScript is: <em>“It’s just JavaScript”</em>. The code compiles one-to-one into the equivalent JS, and there is no interpretation at runtime. You can use any existing JavaScript library seamlessly from C
617offeeScript (and vice-versa). The compiled output is readable, pretty-printed, and tends to run as fast or faster than the equivalent handwritten JavaScript.</p>
618<p>The CoffeeScript compiler goes to great lengths to generate output JavaScript that runs in every JavaScript runtime, but there are exceptions. Use <a href="#generator-functions">generator functions</a>, <a href="#generator-iteration"><code>for…from</code></a>, or <a href="#tagged-template-literals">tagged template literals</a> only if you know that your <a href="http://kangax.github.io/compat-table/es6/">target runtimes can support them</a>. If you use <a href="#modules">modules</a>, you will need to <a href="#modules-note">use an additional tool to resolve them</a>.</p>
619<p><strong>Latest 1.x Version:</strong> <a href="https://github.com/jashkenas/coffeescript/tarball/1.12.7">1.12.7</a></p>
620<blockquote class="uneditable-code-block"><pre><code class="language-bash">npm install -g coffeescript
621</code></pre>
622</blockquote><p><strong>Upgrade to CoffeeScript 2!</strong> It adds support for <a href="/#classes">ES2015 classes</a>, <a href="/#async-functions"><code>async</code>/<code>await</code></a>, <a href="/#jsx">JSX</a>, <span class="nowrap"><a href="/#splats">object rest/spread syntax</a></span>, and <a href="/#coffeescript-2">JavaScript generated using modern syntax</a>. <a href="/announcing-coffeescript-2/">Learn more</a>.</p>
623
624    <h2>Overview</h2>
625<p><em>CoffeeScript on the left, compiled JavaScript output on the right.</em></p>
626<div class='code'><pre><code><span class="comment"># Assignment:</span>
627number   = <span class="number">42</span>
628opposite = <span class="literal">true</span>
629
630<span class="comment"># Conditions:</span>
631number = <span class="number">-42</span> <span class="keyword">if</span> opposite
632
633<span class="comment"># Functions:</span>
634<span class="function"><span class="title">square</span> = <span class="params">(x)</span> -&gt;</span> x * x
635
636<span class="comment"># Arrays:</span>
637list = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>]
638
639<span class="comment"># Objects:</span>
640math =
641  root:   Math.sqrt
642  square: square
643  cube:   <span class="function"><span class="params">(x)</span> -&gt;</span> x * square x
644
645<span class="comment"># Splats:</span>
646<span class="function"><span class="title">race</span> = <span class="params">(winner, runners...)</span> -&gt;</span>
647  <span class="built_in">print</span> winner, runners
648
649<span class="comment"># Existence:</span>
650alert <span class="string">"I knew it!"</span> <span class="keyword">if</span> elvis?
651
652<span class="comment"># Array comprehensions:</span>
653cubes = (math.cube num <span class="keyword">for</span> num <span class="keyword">in</span> list)
654</code></pre><pre><code><span class="keyword">var</span> cubes, list, math, num, number, opposite, race, square,
655  slice = [].slice;
656
657number = <span class="number">42</span>;
658
659opposite = <span class="literal">true</span>;
660
661<span class="keyword">if</span> (opposite) {
662  number = <span class="number">-42</span>;
663}
664
665square = <span class="function"><span class="keyword">function</span>(<span class="params">x</span>
665) </span>{
666  <span class="keyword">return</span> x * x;
667};
668
669list = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>];
670
671math = {
672  <span class="attr">root</span>: <span class="built_in">Math</span>.sqrt,
673  <span class="attr">square</span>: square,
674  <span class="attr">cube</span>: <span class="function"><span class="keyword">function</span>(<span class="params">x</span>) </span>{
675    <span class="keyword">return</span> x * square(x);
676  }
677};
678
679race = <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
680  <span class="keyword">var</span> runners, winner;
681  winner = <span class="built_in">arguments</span>[<span class="number">0</span>], runners = <span class="number">2</span> &lt;= <span class="built_in">arguments</span>.length ? slice.call(<span class="built_in">arguments</span>, <span class="number">1</span>) : [];
682  <span class="keyword">return</span> print(winner, runners);
683};
684
685<span class="keyword">if</span> (<span class="keyword">typeof</span> elvis !== <span class="string">"undefined"</span> &amp;&amp; elvis !== <span class="literal">null</span>) {
686  alert(<span class="string">"I knew it!"</span>);
687}
688
689cubes = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>
689) </span>{
690  <span class="keyword">var</span> i, len, results;
691  results = [];
692  <span class="keyword">for</span> (i = <span class="number">0</span>, len = list.length; i &lt; len; i++) {
693    num = list[i];
694    results.push(math.cube(num));
695  }
696  <span class="keyword">return</span> results;
697})();
698</code></pre>
698<script>window.example1 = "# Assignment:\nnumber   = 42\nopposite = true\n\n# Conditions:\nnumber = -42 if opposite\n\n# Functions:\nsquare = (x) -> x * x\n\n# Arrays:\nlist = [1, 2, 3, 4, 5]\n\n# Objects:\nmath =\n  root:   Math.sqrt\n  square: square\n  cube:   (x) -> x * square x\n\n# Splats:\nrace = (winner, runners...) ->\n  print winner, runners\n\n# Existence:\nalert \"I knew it!\" if elvis?\n\n# Array comprehensions:\ncubes = (math.cube num for num in list)\n"</script>
698<div class="minibutton ok" onclick="javascript: var cubes, list, math, num, number, opposite, race, square,
699  slice = [].slice;
700
701number = 42;
702
703opposite = true;
704
705if (opposite) {
706  number = -42;
707}
708
709square = function(x) {
710  return x * x;
711};
712
713list = [1, 2, 3, 4, 5];
714
715math = {
716  root: Math.sqrt,
717  square: square,
718  cube: function(x) {
719    return x * square(x);
720  }
721};
722
723race = function() {
724  var runners, winner;
725  winner = arguments[0], runners = 2 <= arguments.length ? slice.call(arguments, 1) : [];
726  return print(winner, runners);
727};
728
729if (typeof elvis !== &quot;undefined&quot; && elvis !== null) {
730  alert(&quot;I knew it!&quot;);
731}
732
733cubes = (function() {
734  var i, len, results;
735  results = [];
736  for (i = 0, len = list.length; i < len; i++) {
737    num = list[i];
738    results.push(math.cube(num));
739  }
740  return results;
741})();
742;alert(cubes);">run: cubes</div><br class='clear' /></div>
743  <span class="bookmark" id="installation"></span>
744    <h2>Installation</h2>
745<p>The command-line version of <code>coffee</code> is available as a <a href="https://nodejs.org/">Node.js</a> utility. The <a href="browser-compiler/coffee-script.js">core compiler</a> however, does not depend on Node, and can be run in any JavaScript environment, or in the browser (see <a href="#try">Try CoffeeScript</a>).</p>
746<p>To install, first make sure you have a working copy of the latest stable version of <a href="https://nodejs.org/">Node.js</a>. You can then install CoffeeScript globally with <a href="https://www.npmjs.com/">npm</a>:</p>
747<blockquote class="uneditable-code-block"><pre><code class="language-bash">npm install --global coffeescript
748</code></pre>
749</blockquote><p>This will make the <code>coffee</code> and <code>cake</code> commands available globally.</p>
750<p>When you need CoffeeScript as a dependency of a project, within that project’s folder you can install it locally:</p>
751<blockquote class="uneditable-code-block"><pre><code class="language-bash">npm install --save coffeescript
752</code></pre>
753</blockquote><p>The <code>coffee</code> and <code>cake</code> commands will first look in the current folder to see if CoffeeScript is installed locally, and use that version if so. This allows different versions of CoffeeScript to be installed globally and locally.</p>
754
755  <span class="bookmark" id="usage"></span>
756    <h2>Usage</h2>
757<p>Once installed, you should have access to the <code>coffee</code> command, which can execute scripts, compile <code>.coffee</code> files into <code>.js</code>, and provide an interactive REPL. The <code>coffee</code> command takes the following options:</p>
758<table>
759<thead>
760<tr>
761<th>Option</th>
762<th>Description</th>
763</tr>
764</thead>
765<tbody>
766<tr>
767<td><code>-c, --compile</code></td>
768<td>Compile a <code>.coffee</code> script into a <code>.js</code> JavaScript file of the same name.</td>
769</tr>
770<tr>
771<td><code>-m, --map</code></td>
772<td>Generate source maps alongside the compiled JavaScript files. Adds <code>sourceMappingURL</code> directives to the JavaScript as well.</td>
773</tr>
774<tr>
775<td><code>-M, --inline-map</code></td>
776<td>Just like <code>--map</code>, but include the source map directly in the compiled JavaScript files, rather than in a separate file.</td>
777</tr>
778<tr>
779<td><code>-i, --interactive</code></td>
780<td>Launch an interactive CoffeeScript session to try short snippets. Identical to calling <code>coffee</code> with no arguments.</td>
781</tr>
782<tr>
783<td><code>-o, --output [DIR]</code></td>
784<td>Write out all compiled JavaScript files into the specified directory. Use in conjunction with <code>--compile</code> or <code>--watch</code>.</td>
785</tr>
786<tr>
787<td><code>-w, --watch</code></td>
788<td>Watch files for changes, rerunning the specified command when any file is updated.</td>
789</tr>
790<tr>
791<td><code>-p, --print</code></td>
792<td>Instead of writing out the JavaScript as a file, print it directly to <strong>stdout</strong>.</td>
793</tr>
794<tr>
795<td><code>-s, --stdio</code></td>
796<td>Pipe in CoffeeScript to STDIN and get back JavaScript over STDOUT. Good for use with processes written in other languages. An example:<br><code>cat src/cake.coffee | coffee -sc</code></td>
797</tr>
798<tr>
799<td><code>-l, --literate</code></td>
800<td>Parses the code as Literate CoffeeScript. You only need to specify this when passing in code directly over <strong>stdio</strong>, or using some sort of extension-less file name.</td>
801</tr>
802<tr>
803<td><code>-e, --eval</code></td>
804<td>Compile and print a little snippet of CoffeeScript directly from the command line. For example:<br><code>coffee -e &quot;console.log num for num in [10..1]&quot;</code></td>
805</tr>
806<tr>
807<td><code>-r, --require [MODULE]</code> </td>
808<td><code>require()</code> the given module before starting the REPL or evaluating the code given with the <code>--eval</code> flag.</td>
809</tr>
810<tr>
811<td><code>-b, --bare</code></td>
812<td>Compile the JavaScript without the <a href="#lexical-scope">top-level function safety wrapper</a>.</td>
813</tr>
814<tr>
815<td><code>-t, --tokens</code></td>
816<td>Instead of parsing the CoffeeScript, just lex it, and print out the token stream. Used for debugging the compiler.</td>
817</tr>
818<tr>
819<td><code>-n, --nodes</code></td>
820<td>Instead of compiling the CoffeeScript, just lex and parse it, and print out the parse tree. Used for debugging the compiler.</td>
821</tr>
822<tr>
823<td><code>--nodejs</code></td>
824<td>The <code>node</code> executable has some useful options you can set, such as <code>--debug</code>, <code>--debug-brk</code>, <code>--max-stack-size</code>, and <code>--expose-gc</code>. Use this flag to forward options directly to Node.js. To pass multiple flags, use <code>--nodejs</code> multiple times.</td>
825</tr>
826<tr>
827<td><code>--no-header</code></td>
828<td>Suppress the “Generated by CoffeeScript” header.</td>
829</tr>
830</tbody>
831</table>
832<h3>Examples:</h3>
833<ul>
834<li>Compile a directory tree of <code>.coffee</code> files in <code>src</code> into a parallel tree of <code>.js</code> files in <code>lib</code>:<br>
835<code>coffee --compile --output lib/ src/</code></li>
836<li>Watch a file for changes, and recompile it every time the file is saved:<br>
837<code>coffee --watch --compile experimental.coffee</code></li>
838<li>Concatenate a list of files into a single script:<br>
839<code>coffee --join project.js --compile src/*.coffee</code></li>
840<li>Print out the compiled JS from a one-liner:<br>
841<code>coffee -bpe &quot;alert i for i in [0..10]&quot;</code></li>
842<li>All together now, watch and recompile an entire project as you work on it:<br>
843<code>coffee -o lib/ -cw src/</code></li>
844<li>Start the CoffeeScript REPL (<code>Ctrl-D</code> to exit, <code>Ctrl-V</code>for multi-line):<br>
845<code>coffee</code></li>
846</ul>
847
848  <span class="bookmark" id="literate"></span>
849    <h2>Literate CoffeeScript</h2>
850<p>Besides being used as an ordinary programming language, CoffeeScript may al
850so be written in “literate” mode. If you name your file with a <code>.litcoffee</code> extension, you can write it as a Markdown document — a document that also happens to be executable CoffeeScript code. The compiler will treat any indented blocks (Markdown’s way of indicating source code) as code, and ignore the rest as comments.</p>
851<p>Just for kicks, a little bit of the compiler is currently implemented in this fashion: See it <a href="https://gist.github.com/jashkenas/3fc3c1a8b1009c00d9df">as a document</a>, <a href="https://raw.githubusercontent.com/jashkenas/coffeescript/master/src/scope.litcoffee">raw</a>, and <a href="http://cl.ly/LxEu">properly highlighted in a text editor</a>.</p>
852
853  <span class="bookmark" id="language"></span>
854    <h2>Language Reference</h2>
855<p><em>This reference is structured so that it can be read from top to bottom, if you like. Later sections use ideas and syntax previously introduced. Familiarity with JavaScript is assumed. In all of the following examples, the source CoffeeScript is provided on the left, and the direct compilation into JavaScript is on the right.</em></p>
856<p><em>Many of the examples can be run (where it makes sense) by pressing the <strong>run</strong> button on the right, and can be loaded into the “Try CoffeeScript” console by pressing the <strong>load</strong> button on the left.</em></p>
857<p>First, the basics: CoffeeScript uses significant whitespace to delimit blocks of code. You don’t need to use semicolons <code>;</code> to terminate expressions, ending the line will do just as well (although semicolons can still be used to fit multiple expressions onto a single line). Instead of using curly braces <code>{ }</code> to surround blocks of code in <a href="#literals">functions</a>, <a href="#conditionals">if-statements</a>, <a href="#switch">switch</a>, and <a href="#try-catch">try/catch</a>, use indentation.</p>
858<p>You don’t need to use parentheses to invoke a function if you’re passing arguments. The implicit call wraps forward to the end of the line or block expression.<br>
859<code>console.log sys.inspect object</code> → <code>console.log(sys.inspect(object));</code></p>
860
861    <span class="bookmark" id="literals"></span>
862      <h2>Functions</h2>
863<p>Functions are defined by an optional list of parameters in parentheses, an arrow, and the function body. The empty function looks like this: <code>-&gt;</code></p>
864<div class='code'><pre><code><span class="function"><span class="title">square</span> = <span class="params">(x)</span> -&gt;</span> x * x
865<span class="function"><span class="title">cube</span>   = <span class="params">(x)</span> -&gt;</span> square(x) * x
866</code></pre><pre><code><span class="keyword">var</span> cube, square;
867
868square = <span class="function"><span class="keyword">function</span>(<span class="params">x</span>
868) </span>{
869  <span class="keyword">return</span> x * x;
870};
871
872cube = <span class="function"><span class="keyword">function</span>(<span class="params">x</span>) </span>{
873  <span class="keyword">return</span> square(x) * x;
874};
875</code></pre>
875<script>window.example1 = "square = (x) -> x * x\ncube   = (x) -> square(x) * x\n"</script>
875<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var cube, square;
876
877square = function(x) {
878  return x * x;
879};
880
881cube = function(x) {
882  return square(x) * x;
883};
884;alert(cube(5));">run: cube(5)</div><br class='clear' /></div><p>Functions may also have default values for arguments, which will be used if the incoming argument is missing (<code>null</code> or <code>undefined</code>).</p>
885<div class='code'><pre><code><span class="function"><span class="title">fill</span> = <span class="params">(container, liquid = <span class="string">"coffee"</span>)</span> -&gt;</span>
886  <span class="string">"Filling the <span class="subst">#{container}</span> with <span class="subst">#{liquid}</span>..."</span>
887</code></pre><pre><code><span class="keyword">var</span> fill;
888
889fill = <span class="function"><span class="keyword">function</span>(<span class="params">container, liquid</span>) </span>{
890  <span class="keyword">if</span> (liquid == <span class="literal">null</span>) {
891    liquid = <span class="string">"coffee"</span>;
892  }
893  <span class="keyword">return</span> <span class="string">"Filling the "</span> + container + <span class="string">" with "</span> + liquid + <span class="string">"..."</span>;
894};
895</code></pre>
895<script>window.example2 = "fill = (container, liquid = \"coffee\") ->\n  \"Filling the #{container} with #{liquid}...\"\n"</script>
895<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var fill;
896
897fill = function(container, liquid) {
898  if (liquid == null) {
899    liquid = &quot;coffee&quot;;
900  }
901  return &quot;Filling the &quot; + container + &quot; with &quot; + liquid + &quot;...&quot;;
902};
903;alert(fill(&quot;cup&quot;));">run: fill("cup")</div><br class='clear' /></div>
904    <span class="bookmark" id="objects-and-arrays"></span>
905      <h2>Objects and Arrays</h2>
906<p>The CoffeeScript literals for objects and arrays look very similar to their JavaScript cousins. When each property is listed on its own line, the commas are optional. Objects may be created using indentation instead of explicit braces, similar to <a href="http://yaml.org">YAML</a>.</p>
907<div class='code'><pre><code>song = [<span class="string">"do"</span>, <span class="string">"re"</span>, <span class="string">"mi"</span>, <span class="string">"fa"</span>, <span class="string">"so"</span>]
908
909singers = {Jagger: <span class="string">"Rock"</span>, Elvis: <span class="string">"Roll"</span>}
910
911bitlist = [
912  <span class="number">1</span>, <span class="number">0</span>, <span class="number">1</span>
913  <span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>
914  <span class="number">1</span>, <span class="number">1</span>, <span class="number">0</span>
915]
916
917kids =
918  brother:
919    name: <span class="string">"Max"</span>
920    age:  <span class="number">11</span>
921  sister:
922    name: <span class="string">"Ida"</span>
923    age:  <span class="number">9</span>
924</code></pre><pre><code><span class="keyword">var</span> bitlist, kids, singers, song;
925
926song = [<span class="string">"do"</span>, <span class="string">"re"</span>, <span class="string">"mi"</span>, <span class="string">"fa"</span>, <span class="string">"so"</span>];
927
928singers = {
929  <span class="attr">Jagger</span>: <span class="string">"Rock"</span>,
930  <span class="attr">Elvis</span>: <span class="string">"Roll"</span>
931};
932
933bitlist = [<span class="number">1</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">1</span>, <span class="number">0</span>];
934
935kids = {
936  <span class="attr">brother</span>: {
937    <span class="attr">name</span>: <span class="string">"Max"</span>,
938    <span class="attr">age</span>: <span class="number">11</span>
939  },
940  <span class="attr">sister</span>: {
941    <span class="attr">name</span>: <span class="string">"Ida"</span>,
942    <span class="attr">age</span>: <span class="number">9</span>
943  }
944};
945</code></pre>
945<script>window.example1 = "song = [\"do\", \"re\", \"mi\", \"fa\", \"so\"]\n\nsingers = {Jagger: \"Rock\", Elvis: \"Roll\"}\n\nbitlist = [\n  1, 0, 1\n  0, 0, 1\n  1, 1, 0\n]\n\nkids =\n  brother:\n    name: \"Max\"\n    age:  11\n  sister:\n    name: \"Ida\"\n    age:  9\n"</script>
945<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var bitlist, kids, singers, song;
946
947song = [&quot;do&quot;, &quot;re&quot;, &quot;mi&quot;, &quot;fa&quot;, &quot;so&quot;];
948
949singers = {
950  Jagger: &quot;Rock&quot;,
951  Elvis: &quot;Roll&quot;
952};
953
954bitlist = [1, 0, 1, 0, 0, 1, 1, 1, 0];
955
956kids = {
957  brother: {
958    name: &quot;Max&quot;,
959    age: 11
960  },
961  sister: {
962    name: &quot;Ida&quot;,
963    age: 9
964  }
965};
966;alert(song.join(&quot; … &quot;));">run: song.join(" … ")</div><br class='clear' /></div><p>In JavaScript, you can’t use reserved words, like <code>class</code>, as properties of an object, without quoting them as strings. CoffeeScript notices reserved words used as keys in objects and quotes them for you, so you don’t have to worry about it (say, when using jQuery).</p>
967<div class='code'><pre><code>$('.account').attr class: 'active'
968
969log object.class
970</code></pre><pre><code>$(<span class="string">'.account'</span>).attr({
971  <span class="string">"class"</span>: <span class="string">'active'</span>
972});
973
974log(object[<span class="string">"class"</span>]);
975</code></pre>
975<script>window.example2 = "$('.account').attr class: 'active'\n\nlog object.class\n"</script>
975<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><br class='clear' /></div><p>CoffeeScript has a shortcut for creating objects when you want the key to be set with a variable of the same name.</p>
976<div class='code'><pre><code>name = <span class="string">"Michelangelo"</span>
977mask = <span class="string">"orange"</span>
978weapon = <span class="string">"nunchuks"</span>
979turtle = {name, mask, weapon}
980output = <span class="string">"<span class="subst">#{turtle.name}</span> wears an <span class="subst">#{turtle.mask}</span> mask. Watch out for his <span class="subst">#{turtle.weapon}</span>!"</span>
981</code></pre><pre><code><span class="keyword">var</span> mask, name, output, turtle, weapon;
982
983name = <span class="string">"Michelangelo"</span>;
984
985mask = <span class="string">"orange"</span>;
986
987weapon = <span class="string">"nunchuks"</span>;
988
989turtle = {
990  <span class="attr">name</span>: name,
991  <span class="attr">mask</span>: mask,
992  <span class="attr">weapon</span>: weapon
993};
994
995output = turtle.name + <span class="string">" wears an "</span> + turtle.mask + <span class="string">" mask. Watch out for his "</span> + turtle.weapon + <span class="string">"!"</span>;
996</code></pre>
996<script>window.example3 = "name = \"Michelangelo\"\nmask = \"orange\"\nweapon = \"nunchuks\"\nturtle = {name, mask, weapon}\noutput = \"#{turtle.name} wears an #{turtle.mask} mask. Watch out for his #{turtle.weapon}!\"\n"</script>
996<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><br class='clear' /></div>
997    <span class="bookmark" id="lexical-scope"></span>
998      <h2>Lexical Scoping and Variable Safety</h2>
999<p>The CoffeeScript compiler takes care to make sure that all of your variables are properly declared within lexical scope — you never need to write <code>var</code> yourself.</p>
1000<div class='code'><pre><code>outer = <span class="number">1</span>
1001<span class="function"><span class="title">changeNumbers</span> = -&gt;</span>
1002  inner = <span class="number">-1</span>
1003  outer = <span class="number">10</span>
1004inner = changeNumbers()
1005</code></pre><pre><code><span class="keyword">var</span> changeNumbers, inner, outer;
1006
1007outer = <span class="number">1</span>;
1008
1009changeNumbers = <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1010  <span class="keyword">var</span> inner;
1011  inner = <span class="number">-1</span>;
1012  <span class="keyword">return</span> outer = <span class="number">10</span>;
1013};
1014
1015inner = changeNumbers();
1016</code></pre>
1016<script>window.example1 = "outer = 1\nchangeNumbers = ->\n  inner = -1\n  outer = 10\ninner = changeNumbers()\n"</script>
1016<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var changeNumbers, inner, outer;
1017
1018outer = 1;
1019
1020changeNumbers = function() {
1021  var inner;
1022  inner = -1;
1023  return outer = 10;
1024};
1025
1026inner = changeNumbers();
1027;alert(inner);">run: inner</div><br class='clear' /></div><p>Notice how all of the variable declarations have been pushed up to the top of the closest scope, the first time they appear. <strong>outer</strong> is not redeclared within the inner function, because it’s already in scope; <strong>inner</strong> within the function, on the other hand, should not be able to change the value of the external variable of the same name, and therefore has a declaration of its own.</p>
1028<p>This behavior is effectively identical to Ruby’s scope for local variables. Because you don’t have direct access to the <code>var</code> keyword, it’s impossible to shadow an outer variable on purpose, you may only refer to it. So be careful that you’re not reusing the name of an external variable accidentally, if you’re writing a deeply nested function.</p>
1029<p>Although suppressed within this documentation for clarity, all CoffeeScript output is wrapped in an anonymous function: <code>(function(){ … })();</code> This safety wrapper, combined with the automatic generation of the <code>var</code> keyword, make it exceedingly difficult to pollute the global namespace by accident.</p>
1030<p>If you’d like to create top-level variables for other scripts to use, attach them as properties on <strong>window</strong>; attach them as properties on the <strong>exports</strong> object in CommonJS; or use an <a href="#modules"><code>export</code> statement</a>. If you’re targeting both CommonJS and the browser, the <strong>existential operator</strong> (covered below), gives you a reliable way to figure out where to add them: <code>exports ? this</code></p>
1031
1032    <span class="bookmark" id="conditionals"></span>
1033      <h2>If, Else, Unless, and Conditional Assignment</h2>
1034<p><strong>If/else</strong> statements can be written without the use of parentheses and curly brackets. As with functions and other block expressions, multi-line conditionals are delimited by indentation. There’s also a handy postfix form, with the <code>if</code> or <code>unless</code> at the end.</p>
1035<p>CoffeeScript can compile <strong>if</strong> statements into JavaScript expressions, using the ternary operator when possible, and closure wrapping otherwise. There is no explicit ternary statement in CoffeeScript — you simply use a regular <strong>if</strong> statement on a single line.</p>
1036<div class='code'><pre><code>mood = greatlyImproved <span class="keyword">if</span> singing
1037
1038<span class="keyword">if</span> happy <span class="keyword">and</span> knowsIt
1039  clapsHands()
1040  chaChaCha()
1041<span class="keyword">else</span>
1042  showIt()
1043
1044date = <span class="keyword">if</span> friday <span class="keyword">then</span> sue <span class="keyword">else</span> jill
1045</code></pre><pre><code><span class="keyword">var</span> date, mood;
1046
1047<span class="keyword">if</span> (singing) {
1048  mood = greatlyImproved;
1049}
1050
1051<span class="keyword">if</span> (happy &amp;&amp; knowsIt) {
1052  clapsHands();
1053  chaChaCha();
1054} <span class="keyword">else</span> {
1055  showIt();
1056}
1057
1058date = friday ? sue : jill;
1059</code></pre>
1059<script>window.example1 = "mood = greatlyImproved if singing\n\nif happy and knowsIt\n  clapsHands()\n  chaChaCha()\nelse\n  showIt()\n\ndate = if friday then sue else jill\n"</script>
1059<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div>
1060    <span class="bookmark" id="splats"></span>
1061      <h2>Splats…</h2>
1062<p>The JavaScript <strong>arguments object</strong> is a useful way to work with functions that accept variable numbers of arguments. CoffeeScript provides splats <code>...</code>, both for function definition as well as invocation, making variable numbers of arguments a little bit more palatable.</p>
1063<div class='code'><pre><code>gold = silver = rest = <span class="string">"unknown"</span>
1064<span class="function">
1065<span class="title">awardMedals</span> = <span class="params">(first, second, others...)</span> -&gt;</span>
1066  gold   = first
1067  silver = second
1068  rest   = others
1069
1070contenders = [
1071  <span class="string">"Michael Phelps"</span>
1072  <span class="string">"Liu Xiang"</span>
1073  <span class="string">"Yao Ming"</span>
1074  <span class="string">"Allyson Felix"</span>
1075  <span class="string">"Shawn Johnson"</span>
1076  <span class="string">"Roman Sebrle"</span>
1077  <span class="string">"Guo Jingjing"</span>
1078  <span class="string">"Tyson Gay"</span>
1079  <span class="string">"Asafa Powell"</span>
1080  <span class="string">"Usain Bolt"</span>
1081]
1082
1083awardMedals contenders...
1084
1085alert <span class="string">"Gold: "</span> + gold
1086alert <span class="string">"Silver: "</span> + silver
1087alert <span class="string">"The Field: "</span> + rest
1088</code></pre><pre><code><span class="keyword">var</span> awardMedals, contenders, gold, rest, silver,
1089  slice = [].slice;
1090
1091gold = silver = rest = <span class="string">"unknown"</span>;
1092
1093awardMedals = <span class="function"><span class="keyword">function</span>(<span class="params"></span>
1093) </span>{
1094  <span class="keyword">var</span> first, others, second;
1095  first = <span class="built_in">arguments</span>[<span class="number">0</span>], second = <span class="built_in">arguments</span>[<span class="number">1</span>], others = <span class="number">3</span> &lt;= <span class="built_in">arguments</span>.length ? slice.call(<span class="built_in">arguments</span>, <span class="number">2</span>) : [];
1096  gold = first;
1097  silver = second;
1098  <span class="keyword">return</span> rest = others;
1099};
1100
1101contenders = [<span class="string">"Michael Phelps"</span>, <span class="string">"Liu Xiang"</span>, <span class="string">"Yao Ming"</span>, <span class="string">"Allyson Felix"</span>, <span class="string">"Shawn Johnson"</span>, <span class="string">"Roman Sebrle"</span>, <span class="string">"Guo Jingjing"</span>, <span class="string">"Tyson Gay"</span>, <span class="string">"Asafa Powell"</span>, <span class="string">"Usain Bolt"</span>];
1102
1103awardMedals.apply(<span class="literal">null</span>, contenders);
1104
1105alert(<span class="string">"Gold: "</span> + gold);
1106
1107alert(<span class="string">"Silver: "</span> + silver);
1108
1109alert(<span class="string">"The Field: "</span> + rest);
1110</code></pre>
1110<script>window.example1 = "gold = silver = rest = \"unknown\"\n\nawardMedals = (first, second, others...) ->\n  gold   = first\n  silver = second\n  rest   = others\n\ncontenders = [\n  \"Michael Phelps\"\n  \"Liu Xiang\"\n  \"Yao Ming\"\n  \"Allyson Felix\"\n  \"Shawn Johnson\"\n  \"Roman Sebrle\"\n  \"Guo Jingjing\"\n  \"Tyson Gay\"\n  \"Asafa Powell\"\n  \"Usain Bolt\"\n]\n\nawardMedals contenders...\n\nalert \"Gold: \" + gold\nalert \"Silver: \" + silver\nalert \"The Field: \" + rest\n"</script>
1110<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var awardMedals, contenders, gold, rest, silver,
1111  slice = [].slice;
1112
1113gold = silver = rest = &quot;unknown&quot;;
1114
1115awardMedals = function() {
1116  var first, others, second;
1117  first = arguments[0], second = arguments[1], others = 3 <= arguments.length ? slice.call(arguments, 2) : [];
1118  gold = first;
1119  silver = second;
1120  return rest = others;
1121};
1122
1123contenders = [&quot;Michael Phelps&quot;, &quot;Liu Xiang&quot;, &quot;Yao Ming&quot;, &quot;Allyson Felix&quot;, &quot;Shawn Johnson&quot;, &quot;Roman Sebrle&quot;, &quot;Guo Jingjing&quot;, &quot;Tyson Gay&quot;, &quot;Asafa Powell&quot;, &quot;Usain Bolt&quot;];
1124
1125awardMedals.apply(null, contenders);
1126
1127alert(&quot;Gold: &quot; + gold);
1128
1129alert(&quot;Silver: &quot; + silver);
1130
1131alert(&quot;The Field: &quot; + rest);
1132;">run</div><br class='clear' /></div>
1133    <span class="bookmark" id="loops"></span>
1134      <h2>Loops and Comprehensions</h2>
1135<p>Most of the loops you’ll write in CoffeeScript will be <strong>comprehensions</strong> over arrays, objects, and ranges. Comprehensions replace (and compile into) <strong>for</strong> loops, with optional guard clauses and the value of the current array index. Unlike for loops, array comprehensions are expressions, and can be returned and assigned.</p>
1136<div class='code'><pre><code><span class="comment"># Eat lunch.</span>
1137eat food <span class="keyword">for</span> food <span class="keyword">in</span> [<span class="string">'toast'</span>, <span class="string">'cheese'</span>, <span class="string">'wine'</span>]
1138
1139<span class="comment"># Fine five course dining.</span>
1140courses = [<span class="string">'greens'</span>, <span class="string">'caviar'</span>, <span class="string">'truffles'</span>, <span class="string">'roast'</span>, <span class="string">'cake'</span>]
1141menu i + <span class="number">1</span>, dish <span class="keyword">for</span> dish, i <span class="keyword">in</span> courses
1142
1143<span class="comment"># Health conscious meal.</span>
1144foods = [<span class="string">'broccoli'</span>, <span class="string">'spinach'</span>, <span class="string">'chocolate'</span>]
1145eat food <span class="keyword">for</span> food <span class="keyword">in</span> foods <span class="keyword">when</span> food <span class="keyword">isnt</span> <span class="string">'chocolate'</span>
1146</code></pre><pre><code><span class="keyword">var</span> courses, dish, food, foods, i, j, k, l, len, len1, len2, ref;
1147
1148ref = [<span class="string">'toast'</span>, <span class="string">'cheese'</span>, <span class="string">'wine'</span>];
1149<span class="keyword">for</span> (j = <span class="number">0</span>, len = ref.length; j &lt; len; j++) {
1150  food = ref[j];
1151  eat(food);
1152}
1153
1154courses = [<span class="string">'greens'</span>, <span class="string">'caviar'</span>, <span class="string">'truffles'</span>, <span class="string">'roast'</span>, <span class="string">'cake'</span>];
1155
1156<span class="keyword">for</span> (i = k = <span class="number">0</span>, len1 = courses.length; k &lt; len1; i = ++k) {
1157  dish = courses[i];
1158  menu(i + <span class="number">1</span>, dish);
1159}
1160
1161foods = [<span class="string">'broccoli'</span>, <span class="string">'spinach'</span>, <span class="string">'chocolate'</span>];
1162
1163<span class="keyword">for</span> (l = <span class="number">0</span>, len2 = foods.length; l &lt; len2; l++) {
1164  food = foods[l];
1165  <span class="keyword">if</span> (food !== <span class="string">'chocolate'</span>) {
1166    eat(food);
1167  }
1168}
1169</code></pre>
1169<script>window.example1 = "# Eat lunch.\neat food for food in ['toast', 'cheese', 'wine']\n\n# Fine five course dining.\ncourses = ['greens', 'caviar', 'truffles', 'roast', 'cake']\nmenu i + 1, dish for dish, i in courses\n\n# Health conscious meal.\nfoods = ['broccoli', 'spinach', 'chocolate']\neat food for food in foods when food isnt 'chocolate'\n"</script>
1169<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><p>Comprehensions should be able to handle most places where you otherwise would use a loop, <strong>each</strong>/<strong>forEach</strong>, <strong>map</strong>, or <strong>select</strong>/<strong>filter</strong>, for example:<br>
1170<code>shortNames = (name for name in list when name.length &lt; 5)</code><br>
1171If you know the start and end of your loop, or would like to step through in fixed-size increments, you can use a range to specify the start and end of your comprehension.</p>
1172<div class='code'><pre><code>countdown = (num <span class="keyword">for</span> num <span class="keyword">in</span> [<span class="number">10.</span><span class="number">.1</span>])
1173</code></pre><pre><code><span class="keyword">var</span> countdown, num;
1174
1175countdown = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1176  <span class="keyword">var</span> i, results;
1177  results = [];
1178  <span class="keyword">for</span> (num = i = <span class="number">10</span>; i &gt;= <span class="number">1</span>; num = --i) {
1179    results.push(num);
1180  }
1181  <span class="keyword">return</span> results;
1182})();
1183</code></pre>
1183<script>window.example2 = "countdown = (num for num in [10..1])\n"</script>
1183<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var countdown, num;
1184
1185countdown = (function() {
1186  var i, results;
1187  results = [];
1188  for (num = i = 10; i >= 1; num = --i) {
1189    results.push(num);
1190  }
1191  return results;
1192})();
1193;alert(countdown);">run: countdown</div><br class='clear' /></div><p>Note how because we are assigning the value of the comprehensions to a variable in the example above, CoffeeScript is collecting the result of each iteration into an array. Sometimes functions end with loops that are intended to run only for their side-effects. Be careful that you’re not accidentally returning the results of the comprehension in these cases, by adding a meaningful return value — like <code>true</code> — or <code>null</code>, to the bottom of your function.</p>
1194<p>To step through a range comprehension in fixed-size chunks, use <code>by</code>, for example:
1195<code>evens = (x for x in [0..10] by 2)</code></p>
1196<p>If you don’t need the current iteration value you may omit it:
1197<code>browser.closeCurrentTab() for [0...count]</code></p>
1198<p>Comprehensions can also be used to iterate over the keys and values in an object. Use <code>of</code> to signal comprehension over the properties of an object instead of the values in an array.</p>
1199<div class='code'><pre><code>yearsOld = max: <span class="number">10</span>, ida: <span class="number">9</span>, tim: <span class="number">11</span>
1200
1201ages = <span class="keyword">for</span> child, age <span class="keyword">of</span> yearsOld
1202  <span class="string">"<span class="subst">#{child}</span> is <span class="subst">#{age}</span>"</span>
1203</code></pre><pre><code><span class="keyword">var</span> age, ages, child, yearsOld;
1204
1205yearsOld = {
1206  <span class="attr">max</span>: <span class="number">10</span>,
1207  <span class="attr">ida</span>: <span class="number">9</span>,
1208  <span class="attr">tim</span>: <span class="number">11</span>
1209};
1210
1211ages = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>
1211) </span>{
1212  <span class="keyword">var</span> results;
1213  results = [];
1214  <span class="keyword">for</span> (child <span class="keyword">in</span> yearsOld) {
1215    age = yearsOld[child];
1216    results.push(child + <span class="string">" is "</span> + age);
1217  }
1218  <span class="keyword">return</span> results;
1219})();
1220</code></pre>
1220<script>window.example3 = "yearsOld = max: 10, ida: 9, tim: 11\n\nages = for child, age of yearsOld\n  \"#{child} is #{age}\"\n"</script>
1220<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class="minibutton ok" onclick="javascript: var age, ages, child, yearsOld;
1221
1222yearsOld = {
1223  max: 10,
1224  ida: 9,
1225  tim: 11
1226};
1227
1228ages = (function() {
1229  var results;
1230  results = [];
1231  for (child in yearsOld) {
1232    age = yearsOld[child];
1233    results.push(child + &quot; is &quot; + age);
1234  }
1235  return results;
1236})();
1237;alert(ages.join(&quot;, &quot;));">run: ages.join(", ")</div><br class='clear' /></div><p>If you would like to iterate over just the keys that are defined on the object itself, by adding a <code>hasOwnProperty</code> check to avoid properties that may be inherited from the prototype, use <code>for own key, value of object</code>.</p>
1238<p>To iterate a generator function, use <code>from</code>. See <a href="#generator-iteration">Generator Functions</a>.</p>
1239<p>The only low-level loop that CoffeeScript provides is the <strong>while</strong> loop. The main difference from JavaScript is that the <strong>while</strong> loop can be used as an expression, returning an array containing the result of each iteration through the loop.</p>
1240<div class='code'><pre><code><span class="comment"># Econ 101</span>
1241<span class="keyword">if</span> <span class="keyword">this</span>.studyingEconomics
1242  buy()  <span class="keyword">while</span> supply &gt; demand
1243  sell() <span class="keyword">until</span> supply &gt; demand
1244
1245<span class="comment"># Nursery Rhyme</span>
1246num = <span class="number">6</span>
1247lyrics = <span class="keyword">while</span> num -= <span class="number">1</span>
1248  <span class="string">"<span class="subst">#{num}</span> little monkeys, jumping on the bed.
1249    One fell out and bumped his head."</span>
1250</code></pre><pre><code><span class="keyword">var</span> lyrics, num;
1251
1252<span class="keyword">if</span> (<span class="keyword">this</span>.studyingEconomics) {
1253  <span class="keyword">while</span> (supply &gt; demand) {
1254    buy();
1255  }
1256  <span class="keyword">while</span> (!(supply &gt; demand)) {
1257    sell();
1258  }
1259}
1260
1261num = <span class="number">6</span>;
1262
1263lyrics = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>
1263) </span>{
1264  <span class="keyword">var</span> results;
1265  results = [];
1266  <span class="keyword">while</span> (num -= <span class="number">1</span>) {
1267    results.push(num + <span class="string">" little monkeys, jumping on the bed. One fell out and bumped his head."</span>);
1268  }
1269  <span class="keyword">return</span> results;
1270})();
1271</code></pre>
1271<script>window.example4 = "# Econ 101\nif this.studyingEconomics\n  buy()  while supply > demand\n  sell() until supply > demand\n\n# Nursery Rhyme\nnum = 6\nlyrics = while num -= 1\n  \"#{num} little monkeys, jumping on the bed.\n    One fell out and bumped his head.\"\n"</script>
1271<div class='minibutton load' onclick='javascript: loadConsole(example4);'>load</div><div class="minibutton ok" onclick="javascript: var lyrics, num;
1272
1273if (this.studyingEconomics) {
1274  while (supply > demand) {
1275    buy();
1276  }
1277  while (!(supply > demand)) {
1278    sell();
1279  }
1280}
1281
1282num = 6;
1283
1284lyrics = (function() {
1285  var results;
1286  results = [];
1287  while (num -= 1) {
1288    results.push(num + &quot; little monkeys, jumping on the bed. One fell out and bumped his head.&quot;);
1289  }
1290  return results;
1291})();
1292;alert(lyrics.join(&quot;\n&quot;));">run: lyrics.join("\n")</div><br class='clear' /></div><p>For readability, the <strong>until</strong> keyword is equivalent to <code>while not</code>, and the <strong>loop</strong> keyword is equivalent to <code>while true</code>.</p>
1293<p>When using a JavaScript loop to generate functions, it’s common to insert a closure wrapper in order to ensure that loop variables are closed over, and all the generated functions don’t just share the final values. CoffeeScript provides the <code>do</code> keyword, which immediately invokes a passed function, forwarding any arguments.</p>
1294<div class='code'><pre><code><span class="keyword">for</span> filename <span class="keyword">in</span> list
1295  <span class="keyword">do</span> (filename) -&gt;
1296    fs.readFile filename, <span class="function"><span class="params">(err, contents)</span> -&gt;</span>
1297      compile filename, contents.toString()
1298</code></pre><pre><code><span class="keyword">var</span> filename, fn, i, len;
1299
1300fn = <span class="function"><span class="keyword">function</span>(<span class="params">filename</span>
1300) </span>{
1301  <span class="keyword">return</span> fs.readFile(filename, <span class="function"><span class="keyword">function</span>(<span class="params">err, contents</span>) </span>{
1302    <span class="keyword">return</span> compile(filename, contents.toString());
1303  });
1304};
1305<span class="keyword">for</span> (i = <span class="number">0</span>, len = list.length; i &lt; len; i++) {
1306  filename = list[i];
1307  fn(filename);
1308}
1309</code></pre>
1309<script>window.example5 = "for filename in list\n  do (filename) ->\n    fs.readFile filename, (err, contents) ->\n      compile filename, contents.toString()\n"</script>
1309<div class='minibutton load' onclick='javascript: loadConsole(example5);'>load</div><br class='clear' /></div>
1310    <span class="bookmark" id="slices"></span>
1311      <h2>Array Slicing and Splicing with Ranges</h2>
1312<p>Ranges can also be used to extract slices of arrays. With two dots (<code>3..6</code>), the range is inclusive (<code>3, 4, 5, 6</code>); with three dots (<code>3...6</code>), the range excludes the end (<code>3, 4, 5</code>). Slices indices have useful defaults. An omitted first index defaults to zero and an omitted second index defaults to the size of the array.</p>
1313<div class='code'><pre><code>numbers = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>]
1314
1315start   = numbers[<span class="number">0.</span><span class="number">.2</span>]
1316
1317middle  = numbers[<span class="number">3.</span>..<span class="number">-2</span>]
1318
1319end     = numbers[<span class="number">-2.</span>.]
1320
1321copy    = numbers[..]
1322</code></pre><pre><code><span class="keyword">var</span> copy, end, middle, numbers, start;
1323
1324numbers = [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>];
1325
1326start = numbers.slice(<span class="number">0</span>, <span class="number">3</span>);
1327
1328middle = numbers.slice(<span class="number">3</span>, <span class="number">-2</span>);
1329
1330end = numbers.slice(<span class="number">-2</span>);
1331
1332copy = numbers.slice(<span class="number">0</span>);
1333</code></pre>
1333<script>window.example1 = "numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9]\n\nstart   = numbers[0..2]\n\nmiddle  = numbers[3...-2]\n\nend     = numbers[-2..]\n\ncopy    = numbers[..]\n"</script>
1333<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var copy, end, middle, numbers, start;
1334
1335numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9];
1336
1337start = numbers.slice(0, 3);
1338
1339middle = numbers.slice(3, -2);
1340
1341end = numbers.slice(-2);
1342
1343copy = numbers.slice(0);
1344;alert(middle);">run: middle</div><br class='clear' /></div><p>The same syntax can be used with assignment to replace a segment of an array with new values, splicing it.</p>
1345<div class='code'><pre><code>numbers = [<span class="number">0</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>]
1346
1347numbers[<span class="number">3.</span><span class="number">.6</span>] = [<span class="number">-3</span>, <span class="number">-4</span>, <span class="number">-5</span>, <span class="number">-6</span>]
1348</code></pre><pre><code><span class="keyword">var</span> numbers, ref;
1349
1350numbers = [<span class="number">0</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">9</span>];
1351
1352[].splice.apply(numbers, [<span class="number">3</span>, <span class="number">4</span>].concat(ref = [<span class="number">-3</span>, <span class="number">-4</span>, <span class="number">-5</span>, <span class="number">-6</span>])), ref;
1353</code></pre>
1353<script>window.example2 = "numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n\nnumbers[3..6] = [-3, -4, -5, -6]\n"</script>
1353<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var numbers, ref;
1354
1355numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
1356
1357[].splice.apply(numbers, [3, 4].concat(ref = [-3, -4, -5, -6])), ref;
1358;alert(numbers);">run: numbers</div><br class='clear' /></div><p>Note that JavaScript strings are immutable, and can’t be spliced.</p>
1359
1360    <span class="bookmark" id="expressions"></span>
1361      <h2>Everything is an Expression (at least, as much as possible)</h2>
1362<p>You might have noticed how even though we don’t add return statements to CoffeeScript functions, they nonetheless return their final value. The CoffeeScript compiler tries to make sure that all statements in the language can be used as expressions. Watch how the <code>return</code> gets pushed down into each possible branch of execution in the function below.</p>
1363<div class='code'><pre><code><span class="function"><span class="title">grade</span> = <span class="params">(student)</span> -&gt;</span>
1364  <span class="keyword">if</span> student.excellentWork
1365    <span class="string">"A+"</span>
1366  <span class="keyword">else</span> <span class="keyword">if</span> student.okayStuff
1367    <span class="keyword">if</span> student.triedHard <span class="keyword">then</span> <span class="string">"B"</span> <span class="keyword">else</span> <span class="string">"B-"</span>
1368  <span class="keyword">else</span>
1369    <span class="string">"C"</span>
1370
1371eldest = <span class="keyword">if</span> <span class="number">24</span> &gt; <span class="number">21</span> <span class="keyword">then</span> <span class="string">"Liz"</span> <span class="keyword">else</span> <span class="string">"Ike"</span>
1372</code></pre><pre><code><span class="keyword">var</span> eldest, grade;
1373
1374grade = <span class="function"><span class="keyword">function</span>(<span class="params">student</span>
1374) </span>{
1375  <span class="keyword">if</span> (student.excellentWork) {
1376    <span class="keyword">return</span> <span class="string">"A+"</span>;
1377  } <span class="keyword">else</span> <span class="keyword">if</span> (student.okayStuff) {
1378    <span class="keyword">if</span> (student.triedHard) {
1379      <span class="keyword">return</span> <span class="string">"B"</span>;
1380    } <span class="keyword">else</span> {
1381      <span class="keyword">return</span> <span class="string">"B-"</span>;
1382    }
1383  } <span class="keyword">else</span> {
1384    <span class="keyword">return</span> <span class="string">"C"</span>;
1385  }
1386};
1387
1388eldest = <span class="number">24</span> &gt; <span class="number">21</span> ? <span class="string">"Liz"</span> : <span class="string">"Ike"</span>;
1389</code></pre>
1389<script>window.example1 = "grade = (student) ->\n  if student.excellentWork\n    \"A+\"\n  else if student.okayStuff\n    if student.triedHard then \"B\" else \"B-\"\n  else\n    \"C\"\n\neldest = if 24 > 21 then \"Liz\" else \"Ike\"\n"</script>
1389<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var eldest, grade;
1390
1391grade = function(student) {
1392  if (student.excellentWork) {
1393    return &quot;A+&quot;;
1394  } else if (student.okayStuff) {
1395    if (student.triedHard) {
1396      return &quot;B&quot;;
1397    } else {
1398      return &quot;B-&quot;;
1399    }
1400  } else {
1401    return &quot;C&quot;;
1402  }
1403};
1404
1405eldest = 24 > 21 ? &quot;Liz&quot; : &quot;Ike&quot;;
1406;alert(eldest);">run: eldest</div><br class='clear' /></div><p>Even though functions will always return their final value, it’s both possible and encouraged to return early from a function body writing out the explicit return (<code>return value</code>), when you know that you’re done.</p>
1407<p>Because variable declarations occur at the top of scope, assignment can be used within expressions, even for variables that haven’t been seen before:</p>
1408<div class='code'><pre><code>six = (one = <span class="number">1</span>) + (two = <span class="number">2</span>) + (three = <span class="number">3</span>)
1409</code></pre><pre><code><span class="keyword">var</span> one, six, three, two;
1410
1411six = (one = <span class="number">1</span>) + (two = <span class="number">2</span>) + (three = <span class="number">3</span>);
1412</code></pre>
1412<script>window.example2 = "six = (one = 1) + (two = 2) + (three = 3)\n"</script>
1412<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var one, six, three, two;
1413
1414six = (one = 1) + (two = 2) + (three = 3);
1415;alert(six);">run: six</div><br class='clear' /></div><p>Things that would otherwise be statements in JavaScript, when used as part of an expression in CoffeeScript, are converted into expressions by wrapping them in a closure. This lets you do useful things, like assign the result of a comprehension to a variable:</p>
1416<div class='code'><pre><code><span class="comment"># The first ten global properties.</span>
1417
1418globals = (name <span class="keyword">for</span> name <span class="keyword">of</span> <span class="built_in">window</span>)[<span class="number">0.</span>.<span class="number">.10</span>]
1419</code></pre><pre><code><span class="keyword">var</span> globals, name;
1420
1421globals = ((<span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1422  <span class="keyword">var</span> results;
1423  results = [];
1424  <span class="keyword">for</span> (name <span class="keyword">in</span> <span class="built_in">window</span>) {
1425    results.push(name);
1426  }
1427  <span class="keyword">return</span> results;
1428})()).slice(<span class="number">0</span>, <span class="number">10</span>);
1429</code></pre>
1429<script>window.example3 = "# The first ten global properties.\n\nglobals = (name for name of window)[0...10]\n"</script>
1429<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class="minibutton ok" onclick="javascript: var globals, name;
1430
1431globals = ((function() {
1432  var results;
1433  results = [];
1434  for (name in window) {
1435    results.push(name);
1436  }
1437  return results;
1438})()).slice(0, 10);
1439;alert(globals);">run: globals</div><br class='clear' /></div><p>As well as silly things, like passing a <strong>try/catch</strong> statement directly into a function call:</p>
1440<div class='code'><pre><code>alert(
1441  <span class="keyword">try</span>
1442    nonexistent / <span class="literal">undefined</span>
1443  <span class="keyword">catch</span> error
1444    <span class="string">"And the error is ... <span class="subst">#{error}</span>"</span>
1445)
1446</code></pre><pre><code><span class="keyword">var</span> error;
1447
1448alert((<span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1449  <span class="keyword">try</span> {
1450    <span class="keyword">return</span> nonexistent / <span class="keyword">void</span> <span class="number">0</span>;
1451  } <span class="keyword">catch</span> (error1) {
1452    error = error1;
1453    <span class="keyword">return</span> <span class="string">"And the error is ... "</span> + error;
1454  }
1455})());
1456</code></pre>
1456<script>window.example4 = "alert(\n  try\n    nonexistent / undefined\n  catch error\n    \"And the error is ... #{error}\"\n)\n"</script>
1456<div class='minibutton load' onclick='javascript: loadConsole(example4);'>load</div><div class="minibutton ok" onclick="javascript: var error;
1457
1458alert((function() {
1459  try {
1460    return nonexistent / void 0;
1461  } catch (error1) {
1462    error = error1;
1463    return &quot;And the error is ... &quot; + error;
1464  }
1465})());
1466;">run</div><br class='clear' /></div><p>There are a handful of statements in JavaScript that can’t be meaningfully converted into expressions, namely <code>break</code>, <code>continue</code>, and <code>return</code>. If you make use of them within a block of code, CoffeeScript won’t try to perform the conversion.</p>
1467
1468    <span class="bookmark" id="operators"></span>
1469      <h2>Operators and Aliases</h2>
1470<p>Because the <code>==</code> operator frequently causes undesirable coercion, is intransitive, and has a different meaning than in other languages, CoffeeScript compiles <code>==</code> into <code>===</code>, and <code>!=</code> into <code>!==</code>. In addition, <code>is</code> compiles into <code>===</code>, and <code>isnt</code> into <code>!==</code>.</p>
1471<p>You can use <code>not</code> as an alias for <code>!</code>.</p>
1472<p>For logic, <code>and</code> compiles to <code>&amp;&amp;</code>, and <code>or</code> into <code>||</code>.</p>
1473<p>Instead of a newline or semicolon, <code>then</code> can be used to separate conditions from expressions, in <strong>while</strong>, <strong>if</strong>/<strong>else</strong>, and <strong>switch</strong>/<strong>when</strong> statements.</p>
1474<p>As in <a href="http://yaml.org/">YAML</a>, <code>on</code> and <code>yes</code> are the same as boolean <code>true</code>, while <code>off</code> and <code>no</code> are boolean <code>false</code>.</p>
1475<p><code>unless</code> can be used as the inverse of <code>if</code>.</p>
1476<p>As a shortcut for <code>this.property</code>, you can use <code>@property</code>.</p>
1477<p>You can use <code>in</code> to test for array presence, and <code>of</code> to test for JavaScript object-key presence.</p>
1478<p>To simplify math expressions, <code>**</code> can be used for exponentiation and <code>//</code> performs integer division. <code>%</code> works just like in JavaScript, while <code>%%</code> provides <a href="https://en.wikipedia.org/wiki/Modulo_operation">“dividend dependent modulo”</a>:</p>
1479<div class='code'><pre><code><span class="number">-7</span> % <span class="number">5</span> == <span class="number">-2</span> <span class="comment"># The remainder of 7 / 5</span>
1480<span class="number">-7</span> %% <span class="number">5</span> == <span class="number">3</span> <span class="comment"># n %% 5 is always between 0 and 4</span>
1481
1482tabs.selectTabAtIndex((tabs.currentIndex - count) %% tabs.length)
1483</code></pre><pre><code><span class="keyword">var</span> modulo = <span class="function"><span class="keyword">function</span>(<span class="params">a, b</span>
1483) </span>{ <span class="keyword">return</span> (+a % (b = +b) + b) % b; };
1484
1485<span class="number">-7</span> % <span class="number">5</span> === <span class="number">-2</span>;
1486
1487modulo(<span class="number">-7</span>, <span class="number">5</span>) === <span class="number">3</span>;
1488
1489tabs.selectTabAtIndex(modulo(tabs.currentIndex - count, tabs.length));
1490</code></pre>
1490<script>window.example1 = "-7 % 5 == -2 # The remainder of 7 / 5\n-7 %% 5 == 3 # n %% 5 is always between 0 and 4\n\ntabs.selectTabAtIndex((tabs.currentIndex - count) %% tabs.length)\n"</script>
1490<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><p>All together now:</p>
1491<table>
1492<thead>
1493<tr>
1494<th>CoffeeScript</th>
1495<th>JavaScript</th>
1496</tr>
1497</thead>
1498<tbody>
1499<tr>
1500<td><code>is</code></td>
1501<td><code>===</code></td>
1502</tr>
1503<tr>
1504<td><code>isnt</code></td>
1505<td><code>!==</code></td>
1506</tr>
1507<tr>
1508<td><code>not</code></td>
1509<td><code>!</code></td>
1510</tr>
1511<tr>
1512<td><code>and</code></td>
1513<td><code>&amp;&amp;</code></td>
1514</tr>
1515<tr>
1516<td><code>or</code></td>
1517<td><code>||</code></td>
1518</tr>
1519<tr>
1520<td><code>true</code>, <code>yes</code>, <code>on</code></td>
1521<td><code>true</code></td>
1522</tr>
1523<tr>
1524<td><code>false</code>, <code>no</code>, <code>off</code> </td>
1525<td><code>false</code></td>
1526</tr>
1527<tr>
1528<td><code>@</code>, <code>this</code></td>
1529<td><code>this</code></td>
1530</tr>
1531<tr>
1532<td><code>of</code></td>
1533<td><code>in</code></td>
1534</tr>
1535<tr>
1536<td><code>in</code></td>
1537<td><em>no JS equivalent</em></td>
1538</tr>
1539<tr>
1540<td><code>a ** b</code></td>
1541<td><code>Math.pow(a, b)</code></td>
1542</tr>
1543<tr>
1544<td><code>a // b</code></td>
1545<td><code>Math.floor(a / b)</code></td>
1546</tr>
1547<tr>
1548<td><code>a %% b</code></td>
1549<td><code>(a % b + b) % b</code></td>
1550</tr>
1551</tbody>
1552</table>
1553<div class='code'><pre><code>launch() <span class="keyword">if</span> ignition <span class="keyword">is</span> <span class="literal">on</span>
1554
1555volume = <span class="number">10</span> <span class="keyword">if</span> band <span class="keyword">isnt</span> SpinalTap
1556
1557letTheWildRumpusBegin() <span class="keyword">unless</span> answer <span class="keyword">is</span> <span class="literal">no</span>
1558
1559<span class="keyword">if</span> car.speed &lt; limit <span class="keyword">then</span> accelerate()
1560
1561winner = <span class="literal">yes</span> <span class="keyword">if</span> pick <span class="keyword">in</span> [<span class="number">47</span>, <span class="number">92</span>, <span class="number">13</span>]
1562
1563<span class="built_in">print</span> inspect <span class="string">"My name is <span class="subst">#{@name}</span>"</span>
1564</code></pre><pre><code><span class="keyword">var</span> volume, winner;
1565
1566<span class="keyword">if</span> (ignition === <span class="literal">true</span>) {
1567  launch();
1568}
1569
1570<span class="keyword">if</span> (band !== SpinalTap) {
1571  volume = <span class="number">10</span>;
1572}
1573
1574<span class="keyword">if</span> (answer !== <span class="literal">false</span>) {
1575  letTheWildRumpusBegin();
1576}
1577
1578<span class="keyword">if</span> (car.speed &lt; limit) {
1579  accelerate();
1580}
1581
1582<span class="keyword">if</span> (pick === <span class="number">47</span> || pick === <span class="number">92</span> || pick === <span class="number">13</span>) {
1583  winner = <span class="literal">true</span>;
1584}
1585
1586print(inspect(<span class="string">"My name is "</span> + <span class="keyword">this</span>.name));
1587</code></pre>
1587<script>window.example2 = "launch() if ignition is on\n\nvolume = 10 if band isnt SpinalTap\n\nletTheWildRumpusBegin() unless answer is no\n\nif car.speed < limit then accelerate()\n\nwinner = yes if pick in [47, 92, 13]\n\nprint inspect \"My name is #{@name}\"\n"</script>
1587<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><br class='clear' /></div>
1588    <span class="bookmark" id="existential-operator"></span>
1589      <h2>The Existential Operator</h2>
1590<p>It’s a little difficult to check for the existence of a variable in JavaScript. <code>if (variable) …</code> comes close, but fails for zero, the empty string, and false. CoffeeScript’s existential operator <code>?</code> returns true unless a variable is <strong>null</strong> or <strong>undefined</strong>, which makes it analogous to Ruby’s <code>nil?</code></p>
1591<p>It can also be used for safer conditional assignment than <code>||=</code> provides, for cases where you may be handling numbers or strings.</p>
1592<div class='code'><pre><code>solipsism = <span class="literal">true</span> <span class="keyword">if</span> mind? <span class="keyword">and</span> <span class="keyword">not</span> world?
1593
1594speed = <span class="number">0</span>
1595speed ?= <span class="number">15</span>
1596
1597footprints = yeti ? <span class="string">"bear"</span>
1598</code></pre><pre><code><span class="keyword">var</span> footprints, solipsism, speed;
1599
1600<span class="keyword">if</span> ((<span class="keyword">typeof</span> mind !== <span class="string">"undefined"</span> &amp;&amp; mind !== <span class="literal">null</span>) &amp;&amp; (<span class="keyword">typeof</span> world === <span class="string">"undefined"</span> || world === <span class="literal">null</span>)) {
1601  solipsism = <span class="literal">true</span>;
1602}
1603
1604speed = <span class="number">0</span>;
1605
1606<span class="keyword">if</span> (speed == <span class="literal">null</span>) {
1607  speed = <span class="number">15</span>;
1608}
1609
1610footprints = <span class="keyword">typeof</span> yeti !== <span class="string">"undefined"</span> &amp;&amp; yeti !== <span class="literal">null</span> ? yeti : <span class="string">"bear"</span>;
1611</code></pre>
1611<script>window.example1 = "solipsism = true if mind? and not world?\n\nspeed = 0\nspeed ?= 15\n\nfootprints = yeti ? \"bear\"\n"</script>
1611<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var footprints, solipsism, speed;
1612
1613if ((typeof mind !== &quot;undefined&quot; && mind !== null) && (typeof world === &quot;undefined&quot; || world === null)) {
1614  solipsism = true;
1615}
1616
1617speed = 0;
1618
1619if (speed == null) {
1620  speed = 15;
1621}
1622
1623footprints = typeof yeti !== &quot;undefined&quot; && yeti !== null ? yeti : &quot;bear&quot;;
1624;alert(footprints);">run: footprints</div><br class='clear' /></div><p>The accessor variant of the existential operator <code>?.</code> can be used to soak up null references in a chain of properties. Use it instead of the dot accessor <code>.</code> in cases where the base value may be <strong>null</strong> or <strong>undefined</strong>. If all of the properties exist then you’ll get the expected result, if the chain is broken, <strong>undefined</strong> is returned instead of the <strong>TypeError</strong> that would be raised otherwise.</p>
1625<div class='code'><pre><code>zip = lottery.drawWinner?().address?.zipcode
1626</code></pre><pre><code><span class="keyword">var</span> ref, zip;
1627
1628zip = <span class="keyword">typeof</span> lottery.drawWinner === <span class="string">"function"</span> ? (ref = lottery.drawWinner().address) != <span class="literal">null</span> ? ref.zipcode : <span class="keyword">void</span> <span class="number">0</span> : <span class="keyword">void</span> <span class="number">0</span>;
1629</code></pre>
1629<script>window.example2 = "zip = lottery.drawWinner?().address?.zipcode\n"</script>
1629<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><br class='clear' /></div><p>Soaking up nulls is similar to Ruby’s <a href="https://rubygems.org/gems/andand">andand gem</a>, and to the <a href="http://docs.groovy-lang.org/latest/html/documentation/index.html#_safe_navigation_operator">safe navigation operator</a> in Groovy.</p>
1630
1631    <span class="bookmark" id="classes"></span>
1632      <h2>Classes, Inheritance, and Super</h2>
1633<p>JavaScript’s prototypal inheritance has always been a bit of a brain-bender, with a whole family tree of libraries that provide a cleaner syntax for classical inheritance on top of JavaScript’s prototypes: <a href="https://code.google.com/p/base2/">Base2</a>, <a href="http://prototypejs.org/">Prototype.js</a>, <a href="http://jsclass.jcoglan.com/">JS.Class</a>, etc. The libraries provide syntactic sugar, but the built-in inheritance would be completely usable if it weren’t for a couple of small exceptions: it’s awkward to call <strong>super</strong> (the prototype object’s implementation of the current function), and it’s awkward to correctly set the prototype chain.</p>
1634<p>Instead of repetitively attaching functions to a prototype, CoffeeScript provides a basic <code>class</code> structure that allows you to name your class, set the superclass, assign prototypal properties, and define the constructor, in a single assignable expression.</p>
1635<p>Constructor functions are named, to better support helpful stack traces. In the first class in the example below, <code>this.constructor.name is &quot;Animal&quot;</code>.</p>
1636<div class='code'><pre><code><span class="class"><span class="keyword">class</span> <span class="title">Animal</span></span>
1637  constructor: <span class="function"><span class="params">(@name)</span> -&gt;</span>
1638
1639  move: <span class="function"><span class="params">(meters)</span> -&gt;</span>
1640    alert @name + <span class="string">" moved <span class="subst">#{meters}</span>m."</span>
1641
1642<span class="class"><span class="keyword">class</span> <span class="title">Snake</span> <span class="keyword">extends</span> <span class="title">Animal</span></span>
1643  move: <span class="function">-&gt;</span>
1644    alert <span class="string">"Slithering..."</span>
1645    <span class="keyword">super</span> <span class="number">5</span>
1646
1647<span class="class"><span class="keyword">class</span> <span class="title">Horse</span> <span class="keyword">extends</span> <span class="title">Animal</span></span>
1648  move: <span class="function">-&gt;</span>
1649    alert <span class="string">"Galloping..."</span>
1650    <span class="keyword">super</span> <span class="number">45</span>
1651
1652sam = <span class="keyword">new</span> Snake <span class="string">"Sammy the Python"</span>
1653tom = <span class="keyword">new</span> Horse <span class="string">"Tommy the Palomino"</span>
1654
1655sam.move()
1656tom.move()
1657</code></pre><pre><code><span class="keyword">var</span> Animal, Horse, Snake, sam, tom,
1658  extend = <span class="function"><span class="keyword">function</span>(<span class="params">child, parent</span>
1658) </span>{ <span class="keyword">for</span> (<span class="keyword">var</span> key <span class="keyword">in</span> parent) { <span class="keyword">if</span> (hasProp.call(parent, key)) child[key] = parent[key]; } <span class="function"><span class="keyword">function</span> <span class="title">ctor</span>(<span class="params"></span>) </span>{ <span class="keyword">this</span>.constructor = child; } ctor.prototype = parent.prototype; child.prototype = <span class="keyword">new</span> ctor(); child.__super__ = parent.prototype; <span class="keyword">return</span> child; },
1659  hasProp = {}.hasOwnProperty;
1660
1661Animal = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1662  <span class="function"><span class="keyword">function</span> <span class="title">Animal</span>(<span class="params">name</span>) </span>{
1663    <span class="keyword">this</span>.name = name;
1664  }
1665
1666  Animal.prototype.move = <span class="function"><span class="keyword">function</span>(<span class="params">meters</span>
1666) </span>{
1667    <span class="keyword">return</span> alert(<span class="keyword">this</span>.name + (<span class="string">" moved "</span> + meters + <span class="string">"m."</span>));
1668  };
1669
1670  <span class="keyword">return</span> Animal;
1671
1672})();
1673
1674Snake = (<span class="function"><span class="keyword">function</span>(<span class="params">superClass</span>) </span>{
1675  extend(Snake, superClass);
1676
1677  <span class="function"><span class="keyword">function</span> <span class="title">Snake</span>(<span class="params"></span>) </span>{
1678    <span class="keyword">return</span> Snake.__super__.constructor.apply(<span class="keyword">this</span>, <span class="built_in">arguments</span>);
1679  }
1680
1681  Snake.prototype.move = <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1682    alert(<span class="string">"Slithering..."</span>);
1683    <span class="keyword">return</span> Snake.__super__.move.call(<span class="keyword">this</span>, <span class="number">5</span>);
1684  };
1685
1686  <span class="keyword">return</span> Snake;
1687
1688})(Animal);
1689
1690Horse = (<span class="function"><span class="keyword">function</span>(<span class="params">superClass</span>
1690) </span>{
1691  extend(Horse, superClass);
1692
1693  <span class="function"><span class="keyword">function</span> <span class="title">Horse</span>(<span class="params"></span>) </span>{
1694    <span class="keyword">return</span> Horse.__super__.constructor.apply(<span class="keyword">this</span>, <span class="built_in">arguments</span>);
1695  }
1696
1697  Horse.prototype.move = <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
1698    alert(<span class="string">"Galloping..."</span>);
1699    <span class="keyword">return</span> Horse.__super__.move.call(<span class="keyword">this</span>, <span class="number">45</span>);
1700  };
1701
1702  <span class="keyword">return</span> Horse;
1703
1704})(Animal);
1705
1706sam = <span class="keyword">new</span> Snake(<span class="string">"Sammy the Python"</span>);
1707
1708tom = <span class="keyword">new</span> Horse(<span class="string">"Tommy the Palomino"</span>);
1709
1710sam.move();
1711
1712tom.move();
1713</code></pre>
1713<script>window.example1 = "class Animal\n  constructor: (@name) ->\n\n  move: (meters) ->\n    alert @name + \" moved #{meters}m.\"\n\nclass Snake extends Animal\n  move: ->\n    alert \"Slithering...\"\n    super 5\n\nclass Horse extends Animal\n  move: ->\n    alert \"Galloping...\"\n    super 45\n\nsam = new Snake \"Sammy the Python\"\ntom = new Horse \"Tommy the Palomino\"\n\nsam.move()\ntom.move()\n"</script>
1713<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var Animal, Horse, Snake, sam, tom,
1714  extend = function(child, parent) { for (var key in parent) { if (hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; },
1715  hasProp = {}.hasOwnProperty;
1716
1717Animal = (function() {
1718  function Animal(name) {
1719    this.name = name;
1720  }
1721
1722  Animal.prototype.move = function(meters) {
1723    return alert(this.name + (&quot; moved &quot; + meters + &quot;m.&quot;));
1724  };
1725
1726  return Animal;
1727
1728})();
1729
1730Snake = (function(superClass) {
1731  extend(Snake, superClass);
1732
1733  function Snake() {
1734    return Snake.__super__.constructor.apply(this, arguments);
1735  }
1736
1737  Snake.prototype.move = function() {
1738    alert(&quot;Slithering...&quot;);
1739    return Snake.__super__.move.call(this, 5);
1740  };
1741
1742  return Snake;
1743
1744})(Animal);
1745
1746Horse = (function(superClass) {
1747  extend(Horse, superClass);
1748
1749  function Horse() {
1750    return Horse.__super__.constructor.apply(this, arguments);
1751  }
1752
1753  Horse.prototype.move = function() {
1754    alert(&quot;Galloping...&quot;);
1755    return Horse.__super__.move.call(this, 45);
1756  };
1757
1758  return Horse;
1759
1760})(Animal);
1761
1762sam = new Snake(&quot;Sammy the Python&quot;);
1763
1764tom = new Horse(&quot;Tommy the Palomino&quot;);
1765
1766sam.move();
1767
1768tom.move();
1769;">run</div><br class='clear' /></div><p>If structuring your prototypes classically isn’t your cup of tea, CoffeeScript provides a couple of lower-level conveniences. The <code>extends</code> operator helps with proper prototype setup, and can be used to create an inheritance chain between any pair of constructor functions; <code>::</code> gives you quick access to an object’s prototype; and <code>super()</code> is converted into a call against the immediate ancestor’s method of the same name.</p>
1770<div class='code'><pre><code>String::dasherize = <span class="function">-&gt;</span>
1771  <span class="keyword">this</span>.replace <span class="regexp">/_/g</span>, <span class="string">"-"</span>
1772</code></pre><pre><code><span class="built_in">String</span>.prototype.dasherize = <span class="function"><span class="keyword">function</span>(<span class="params"></span>
1772) </span>{
1773  <span class="keyword">return</span> <span class="keyword">this</span>.replace(<span class="regexp">/_/g</span>, <span class="string">"-"</span>);
1774};
1775</code></pre>
1775<script>window.example2 = "String::dasherize = ->\n  this.replace /_/g, \"-\"\n"</script>
1775<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: String.prototype.dasherize = function() {
1776  return this.replace(/_/g, &quot;-&quot;);
1777};
1778;alert(&quot;one_two&quot;.dasherize());">run: "one_two".dasherize()</div><br class='clear' /></div><p>Finally, class definitions are blocks of executable code, which make for interesting metaprogramming possibilities. Because in the context of a class definition, <code>this</code> is the class object itself (the constructor function), you can assign static properties by using
1779<code>@property: value</code>, and call functions defined in parent classes: <code>@attr 'title', type: 'text'</code></p>
1780
1781    <span class="bookmark" id="destructuring"></span>
1782      <h2>Destructuring Assignment</h2>
1783<p>Just like JavaScript (since ES2015), CoffeeScript has destructuring assignment syntax. When you assign an array or object literal to a value, CoffeeScript breaks up and matches both sides against each other, assigning the values on the right to the variables on the left. In the simplest case, it can be used for parallel assignment:</p>
1784<div class='code'><pre><code>theBait   = <span class="number">1000</span>
1785theSwitch = <span class="number">0</span>
1786
1787[theBait, theSwitch] = [theSwitch, theBait]
1788</code></pre><pre><code><span class="keyword">var</span> ref, theBait, theSwitch;
1789
1790theBait = <span class="number">1000</span>;
1791
1792theSwitch = <span class="number">0</span>;
1793
1794ref = [theSwitch, theBait], theBait = ref[<span class="number">0</span>], theSwitch = ref[<span class="number">1</span>];
1795</code></pre>
1795<script>window.example1 = "theBait   = 1000\ntheSwitch = 0\n\n[theBait, theSwitch] = [theSwitch, theBait]\n"</script>
1795<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var ref, theBait, theSwitch;
1796
1797theBait = 1000;
1798
1799theSwitch = 0;
1800
1801ref = [theSwitch, theBait], theBait = ref[0], theSwitch = ref[1];
1802;alert(theBait);">run: theBait</div><br class='clear' /></div><p>But it’s also helpful for dealing with functions that return multiple values.</p>
1803<div class='code'><pre><code><span class="function"><span class="title">weatherReport</span> = <span class="params">(location)</span> -&gt;</span>
1804  <span class="comment"># Make an Ajax request to fetch the weather...</span>
1805  [location, <span class="number">72</span>, <span class="string">"Mostly Sunny"</span>]
1806
1807[city, temp, forecast] = weatherReport <span class="string">"Berkeley, CA"</span>
1808</code></pre><pre><code><span class="keyword">var</span> city, forecast, ref, temp, weatherReport;
1809
1810weatherReport = <span class="function"><span class="keyword">function</span>(<span class="params">location</span>) </span>{
1811  <span class="keyword">return</span> [location, <span class="number">72</span>, <span class="string">"Mostly Sunny"</span>];
1812};
1813
1814ref = weatherReport(<span class="string">"Berkeley, CA"</span>), city = ref[<span class="number">0</span>], temp = ref[<span class="number">1</span>], forecast = ref[<span class="number">2</span>];
1815</code></pre>
1815<script>window.example2 = "weatherReport = (location) ->\n  # Make an Ajax request to fetch the weather...\n  [location, 72, \"Mostly Sunny\"]\n\n[city, temp, forecast] = weatherReport \"Berkeley, CA\"\n"</script>
1815<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var city, forecast, ref, temp, weatherReport;
1816
1817weatherReport = function(location) {
1818  return [location, 72, &quot;Mostly Sunny&quot;];
1819};
1820
1821ref = weatherReport(&quot;Berkeley, CA&quot;), city = ref[0], temp = ref[1], forecast = ref[2];
1822;alert(forecast);">run: forecast</div><br class='clear' /></div><p>Destructuring assignment can be used with any depth of array and object nesting, to help pull out deeply nested properties.</p>
1823<div class='code'><pre><code>futurists =
1824  sculptor: <span class="string">"Umberto Boccioni"</span>
1825  painter:  <span class="string">"Vladimir Burliuk"</span>
1826  poet:
1827    name:   <span class="string">"F.T. Marinetti"</span>
1828    address: [
1829      <span class="string">"Via Roma 42R"</span>
1830      <span class="string">"Bellagio, Italy 22021"</span>
1831    ]
1832
1833{sculptor} = futurists
1834
1835{poet: {name, address: [street, city]}} = futurists
1836</code></pre><pre><code><span class="keyword">var</span> city, futurists, name, ref, ref1, sculptor, street;
1837
1838futurists = {
1839  <span class="attr">sculptor</span>: <span class="string">"Umberto Boccioni"</span>,
1840  <span class="attr">painter</span>: <span class="string">"Vladimir Burliuk"</span>,
1841  <span class="attr">poet</span>: {
1842    <span class="attr">name</span>: <span class="string">"F.T. Marinetti"</span>,
1843    <span class="attr">address</span>: [<span class="string">"Via Roma 42R"</span>, <span class="string">"Bellagio, Italy 22021"</span>]
1844  }
1845};
1846
1847sculptor = futurists.sculptor;
1848
1849ref = futurists.poet, name = ref.name, (ref1 = ref.address, street = ref1[<span class="number">0</span>], city = ref1[<span class="number">1</span>]);
1850</code></pre>
1850<script>window.example3 = "futurists =\n  sculptor: \"Umberto Boccioni\"\n  painter:  \"Vladimir Burliuk\"\n  poet:\n    name:   \"F.T. Marinetti\"\n    address: [\n      \"Via Roma 42R\"\n      \"Bellagio, Italy 22021\"\n    ]\n\n{sculptor} = futurists\n\n{poet: {name, address: [street, city]}} = futurists\n"</script>
1850<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class="minibutton ok" onclick="javascript: var city, futurists, name, ref, ref1, sculptor, street;
1851
1852futurists = {
1853  sculptor: &quot;Umberto Boccioni&quot;,
1854  painter: &quot;Vladimir Burliuk&quot;,
1855  poet: {
1856    name: &quot;F.T. Marinetti&quot;,
1857    address: [&quot;Via Roma 42R&quot;, &quot;Bellagio, Italy 22021&quot;]
1858  }
1859};
1860
1861sculptor = futurists.sculptor;
1862
1863ref = futurists.poet, name = ref.name, (ref1 = ref.address, street = ref1[0], city = ref1[1]);
1864;alert(name + &quot;-&quot; + street);">run: name + "-" + street</div><br class='clear' /></div><p>Destructuring assignment can even be combined with splats.</p>
1865<div class='code'><pre><code>tag = <span class="string">"&lt;impossible&gt;"</span>
1866
1867[open, contents..., close] = tag.split(<span class="string">""</span>)
1868</code></pre><pre><code><span class="keyword">var</span> close, contents, i, open, ref, tag,
1869  slice = [].slice;
1870
1871tag = <span class="string">"&lt;impossible&gt;"</span>;
1872
1873ref = tag.split(<span class="string">""</span>), open = ref[<span class="number">0</span>], contents = <span class="number">3</span> &lt;= ref.length ? slice.call(ref, <span class="number">1</span>, i = ref.length - <span class="number">1</span>) : (i = <span class="number">1</span>, []), close = ref[i++];
1874</code></pre>
1874<script>window.example4 = "tag = \"<impossible>\"\n\n[open, contents..., close] = tag.split(\"\")\n"</script>
1874<div class='minibutton load' onclick='javascript: loadConsole(example4);'>load</div><div class="minibutton ok" onclick="javascript: var close, contents, i, open, ref, tag,
1875  slice = [].slice;
1876
1877tag = &quot;<impossible>&quot;;
1878
1879ref = tag.split(&quot;&quot;), open = ref[0], contents = 3 <= ref.length ? slice.call(ref, 1, i = ref.length - 1) : (i = 1, []), close = ref[i++];
1880;alert(contents.join(&quot;&quot;));">run: contents.join("")</div><br class='clear' /></div><p>Expansion can be used to retrieve elements from the end of an array without having to assign the rest of its values. It works in function parameter lists as well.</p>
1881<div class='code'><pre><code>text = <span class="string">"Every literary critic believes he will
1882        outwit history and have the last word"</span>
1883
1884[first, ..., last] = text.split <span class="string">" "</span>
1885</code></pre><pre><code><span class="keyword">var</span> first, last, ref, text;
1886
1887text = <span class="string">"Every literary critic believes he will outwit history and have the last word"</span>;
1888
1889ref = text.split(<span class="string">" "</span>), first = ref[<span class="number">0</span>], last = ref[ref.length - <span class="number">1</span>];
1890</code></pre>
1890<script>window.example5 = "text = \"Every literary critic believes he will\n        outwit history and have the last word\"\n\n[first, ..., last] = text.split \" \"\n"</script>
1890<div class='minibutton load' onclick='javascript: loadConsole(example5);'>load</div><div class="minibutton ok" onclick="javascript: var first, last, ref, text;
1891
1892text = &quot;Every literary critic believes he will outwit history and have the last word&quot;;
1893
1894ref = text.split(&quot; &quot;), first = ref[0], last = ref[ref.length - 1];
1895;alert(first + &quot; &quot; + last);">run: first + " " + last</div><br class='clear' /></div><p>Destructuring assignment is also useful when combined with class constructors to assign properties to your instance from an options object passed to the constructor.</p>
1896<div class='code'><pre><code><span class="class"><span class="keyword">class</span> <span class="title">Person</span></span>
1897  constructor: <span class="function"><span class="params">(options)</span> -&gt;</span>
1898    {@name, @age, @height = <span class="string">'average'</span>} = options
1899
1900tim = <span class="keyword">new</span> Person name: <span class="string">'Tim'</span>, age: <span class="number">4</span>
1901</code></pre><pre><code><span class="keyword">var</span> Person, tim;
1902
1903Person = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>
1903) </span>{
1904  <span class="function"><span class="keyword">function</span> <span class="title">Person</span>(<span class="params">options</span>) </span>{
1905    <span class="keyword">var</span> ref;
1906    <span class="keyword">this</span>.name = options.name, <span class="keyword">this</span>.age = options.age, <span class="keyword">this</span>.height = (ref = options.height) != <span class="literal">null</span> ? ref : <span class="string">'average'</span>;
1907  }
1908
1909  <span class="keyword">return</span> Person;
1910
1911})();
1912
1913tim = <span class="keyword">new</span> Person({
1914  <span class="attr">name</span>: <span class="string">'Tim'</span>,
1915  <span class="attr">age</span>: <span class="number">4</span>
1916});
1917</code></pre>
1917<script>window.example6 = "class Person\n  constructor: (options) ->\n    {@name, @age, @height = 'average'} = options\n\ntim = new Person name: 'Tim', age: 4\n"</script>
1917<div class='minibutton load' onclick='javascript: loadConsole(example6);'>load</div><div class="minibutton ok" onclick="javascript: var Person, tim;
1918
1919Person = (function() {
1920  function Person(options) {
1921    var ref;
1922    this.name = options.name, this.age = options.age, this.height = (ref = options.height) != null ? ref : 'average';
1923  }
1924
1925  return Person;
1926
1927})();
1928
1929tim = new Person({
1930  name: 'Tim',
1931  age: 4
1932});
1933;alert(tim.age + &quot; &quot; + tim.height);">run: tim.age + " " + tim.height</div><br class='clear' /></div><p>The above example also demonstrates that if properties are missing in the destructured object or array, you can, just like in JavaScript, provide defaults. The difference with JavaScript is that CoffeeScript, as always, treats both null and undefined the same.</p>
1934
1935    <span class="bookmark" id="fat-arrow"></span>
1936      <h2>Bound Functions, Generator Functions</h2>
1937<p>In JavaScript, the <code>this</code> keyword is dynamically scoped to mean the object that the current function is attached to. If you pass a function as a callback or attach it to a different object, the original value of <code>this</code> will be lost. If you’re not familiar with this behavior, <a href="http://64.13.255.16/articles/scope_in_javascript/">this Digital Web article</a> gives a good overview of the quirks.</p>
1938<p>The fat arrow <code>=&gt;</code> can be used to both define a function, and to bind it to the current value of <code>this</code>, right on the spot. This is helpful when using callback-based libraries like Prototype or jQuery, for creating iterator functions to pass to <code>each</code>, or event-handler functions to use with <code>on</code>. Functions created with the fat arrow are able to access properties of the <code>this</code> where they’re defined.</p>
1939<div class='code'><pre><code><span class="function"><span class="title">Account</span> = <span class="params">(customer, cart)</span> -&gt;</span>
1940  @customer = customer
1941  @cart = cart
1942
1943  $(<span class="string">'.shopping_cart'</span>).<span class="literal">on</span> <span class="string">'click'</span>, <span class="function"><span class="params">(event)</span> =&gt;</span>
1944    @customer.purchase @cart
1945</code></pre><pre><code><span class="keyword">var</span> Account;
1946
1947Account = <span class="function"><span class="keyword">function</span>(<span class="params">customer, cart</span>
1947) </span>{
1948  <span class="keyword">this</span>.customer = customer;
1949  <span class="keyword">this</span>.cart = cart;
1950  <span class="keyword">return</span> $(<span class="string">'.shopping_cart'</span>).on(<span class="string">'click'</span>, (<span class="function"><span class="keyword">function</span>(<span class="params">_this</span>) </span>{
1951    <span class="keyword">return</span> <span class="function"><span class="keyword">function</span>(<span class="params">event</span>) </span>{
1952      <span class="keyword">return</span> _this.customer.purchase(_this.cart);
1953    };
1954  })(<span class="keyword">this</span>));
1955};
1956</code></pre>
1956<script>window.example1 = "Account = (customer, cart) ->\n  @customer = customer\n  @cart = cart\n\n  $('.shopping_cart').on 'click', (event) =>\n    @customer.purchase @cart\n"</script>
1956<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><p>If we had used <code>-&gt;</code> in the callback above, <code>@customer</code> would have referred to the undefined “customer” property of the DOM element, and trying to call <code>purchase()</code> on it would have raised an exception.</p>
1957<p>When used in a class definition, methods declared with the fat arrow will be automatically bound to each instance of the class when the instance is constructed.</p>
1958<div id="generator-functions" class="bookmark"></div>
1959<p>CoffeeScript functions also support <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function*">ES2015 generator functions</a> through the <code>yield</code> keyword. There’s no <code>function*(){}</code> nonsense — a generator in CoffeeScript is simply a function that yields.</p>
1960<div class='code'><pre><code><span class="function"><span class="title">perfectSquares</span> = -&gt;</span>
1961  num = <span class="number">0</span>
1962  <span class="keyword">loop</span>
1963    num += <span class="number">1</span>
1964    <span class="keyword">yield</span> num * num
1965  <span class="keyword">return</span>
1966
1967<span class="built_in">window</span>.ps <span class="keyword">or</span>= perfectSquares()
1968</code></pre><pre><code><span class="keyword">var</span> perfectSquares;
1969
1970perfectSquares = <span class="function"><span class="keyword">function</span>*(<span class="params"></span>
1970) </span>{
1971  <span class="keyword">var</span> num;
1972  num = <span class="number">0</span>;
1973  <span class="keyword">while</span> (<span class="literal">true</span>) {
1974    num += <span class="number">1</span>;
1975    <span class="keyword">yield</span> num * num;
1976  }
1977};
1978
1979<span class="built_in">window</span>.ps || (<span class="built_in">window</span>.ps = perfectSquares());
1980</code></pre>
1980<script>window.example2 = "perfectSquares = ->\n  num = 0\n  loop\n    num += 1\n    yield num * num\n  return\n\nwindow.ps or= perfectSquares()\n"</script>
1980<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var perfectSquares;
1981
1982perfectSquares = function*() {
1983  var num;
1984  num = 0;
1985  while (true) {
1986    num += 1;
1987    yield num * num;
1988  }
1989};
1990
1991window.ps || (window.ps = perfectSquares());
1992;alert(ps.next().value);">run: ps.next().value</div><br class='clear' /></div><p><code>yield*</code> is called <code>yield from</code>, and <code>yield return</code> may be used if you need to force a generator that doesn’t yield.</p>
1993<div id="generator-iteration" class="bookmark"></div>
1994<p>You can iterate over a generator function using <code>for…from</code>.</p>
1995<div class='code'><pre><code><span class="function"><span class="title">fibonacci</span> = -&gt;</span>
1996  [previous, current] = [<span class="number">1</span>, <span class="number">1</span>]
1997  <span class="keyword">loop</span>
1998    [previous, current] = [current, previous + current]
1999    <span class="keyword">yield</span> current
2000  <span class="keyword">return</span>
2001<span class="function">
2002<span class="title">getFibonacciNumbers</span> = <span class="params">(length)</span> -&gt;</span>
2003  results = [<span class="number">1</span>]
2004  <span class="keyword">for</span> n <span class="keyword">from</span> fibonacci()
2005    results.push n
2006    <span class="keyword">break</span> <span class="keyword">if</span> results.length <span class="keyword">is</span> length
2007  results
2008</code></pre><pre><code><span class="keyword">var</span> fibonacci, getFibonacciNumbers;
2009
2010fibonacci = <span class="function"><span class="keyword">function</span>*(<span class="params"></span>
2010) </span>{
2011  <span class="keyword">var</span> current, previous, ref, ref1;
2012  ref = [<span class="number">1</span>, <span class="number">1</span>], previous = ref[<span class="number">0</span>], current = ref[<span class="number">1</span>];
2013  <span class="keyword">while</span> (<span class="literal">true</span>) {
2014    ref1 = [current, previous + current], previous = ref1[<span class="number">0</span>], current = ref1[<span class="number">1</span>];
2015    <span class="keyword">yield</span> current;
2016  }
2017};
2018
2019getFibonacciNumbers = <span class="function"><span class="keyword">function</span>(<span class="params">length</span>) </span>{
2020  <span class="keyword">var</span> n, ref, results;
2021  results = [<span class="number">1</span>];
2022  ref = fibonacci();
2023  <span class="keyword">for</span> (n <span class="keyword">of</span> ref) {
2024    results.push(n);
2025    <span class="keyword">if</span> (results.length === length) {
2026      <span class="keyword">break</span>;
2027    }
2028  }
2029  <span class="keyword">return</span> results;
2030};
2031</code></pre>
2031<script>window.example3 = "fibonacci = ->\n  [previous, current] = [1, 1]\n  loop\n    [previous, current] = [current, previous + current]\n    yield current\n  return\n\ngetFibonacciNumbers = (length) ->\n  results = [1]\n  for n from fibonacci()\n    results.push n\n    break if results.length is length\n  results\n"</script>
2031<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class="minibutton ok" onclick="javascript: var fibonacci, getFibonacciNumbers;
2032
2033fibonacci = function*() {
2034  var current, previous, ref, ref1;
2035  ref = [1, 1], previous = ref[0], current = ref[1];
2036  while (true) {
2037    ref1 = [current, previous + current], previous = ref1[0], current = ref1[1];
2038    yield current;
2039  }
2040};
2041
2042getFibonacciNumbers = function(length) {
2043  var n, ref, results;
2044  results = [1];
2045  ref = fibonacci();
2046  for (n of ref) {
2047    results.push(n);
2048    if (results.length === length) {
2049      break;
2050    }
2051  }
2052  return results;
2053};
2054;alert(getFibonacciNumbers(10));">run: getFibonacciNumbers(10)</div><br class='clear' /></div>
2055    <span class="bookmark" id="embedded"></span>
2056      <h2>Embedded JavaScript</h2>
2057<p>Hopefully, you’ll never need to use it, but if you ever need to intersperse snippets of JavaScript within your CoffeeScript, you can use backticks to pass it straight through.</p>
2058<div class='code'><pre><code>hi = `<span class="javascript"><span class="function"><span class="keyword">function</span>(<span class="params"></span>
2058) </span>{
2059  <span class="keyword">return</span> [<span class="built_in">document</span>.title, <span class="string">"Hello JavaScript"</span>].join(<span class="string">": "</span>);
2060}</span>`
2061</code></pre><pre><code><span class="keyword">var</span> hi;
2062
2063hi = <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
2064  <span class="keyword">return</span> [<span class="built_in">document</span>.title, <span class="string">"Hello JavaScript"</span>].join(<span class="string">": "</span>);
2065};
2066</code></pre>
2066<script>window.example1 = "hi = `function() {\n  return [document.title, \"Hello JavaScript\"].join(\": \");\n}`\n"</script>
2066<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var hi;
2067
2068hi = function() {
2069  return [document.title, &quot;Hello JavaScript&quot;].join(&quot;: &quot;);
2070};
2071;alert(hi());">run: hi()</div><br class='clear' /></div><p>Escape backticks with backslashes: <code>\`​</code> becomes <code>`​</code>.</p>
2072<p>Escape backslashes before backticks with more backslashes: <code>\\\`​</code> becomes <code>\`​</code>.</p>
2073<div class='code'><pre><code>markdown = `<span class="javascript"><span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>{
2074  <span class="keyword">return</span> \</span>`In Markdown, write code like \\\`<span class="javascript"><span class="keyword">this</span>\\\</span>`\`<span class="javascript">;
2075}</span>`
2076</code></pre><pre><code><span class="keyword">var</span> markdown;
2077
2078markdown = <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>{
2079  <span class="keyword">return</span> <span class="string">`In Markdown, write code like \`this\``</span>;
2080};
2081</code></pre>
2081<script>window.example2 = "markdown = `function () {\n  return \\`In Markdown, write code like \\\\\\`this\\\\\\`\\`;\n}`\n"</script>
2081<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var markdown;
2082
2083markdown = function () {
2084  return `In Markdown, write code like \`this\``;
2085};
2086;alert(markdown());">run: markdown()</div><br class='clear' /></div><p>You can also embed blocks of JavaScript using triple backticks. That’s easier than escaping backticks, if you need them inside your JavaScript block.</p>
2087<div class='code'><pre><code>```<span class="javascript">
2088<span class="function"><span class="keyword">function</span> <span class="title">time</span>(<span class="params"></span>) </span>{
2089  <span class="keyword">return</span> <span class="string">`The time is <span class="subst">${<span class="keyword">new</span> <span class="built_in">Date</span>().toLocaleTimeString()}</span>`</span>;
2090}
2091</span>```
2092</code></pre><pre><code>
2093<span class="function"><span class="keyword">function</span> <span class="title">time</span>(<span class="params"></span>) </span>{
2094  <span class="keyword">return</span> <span class="string">`The time is <span class="subst">${<span class="keyword">new</span> <span class="built_in">Date</span>().toLocaleTimeString()}</span>`</span>;
2095}
2096;
2097
2098</code></pre>
2098<script>window.example3 = "```\nfunction time() {\n  return `The time is ${new Date().toLocaleTimeString()}`;\n}\n```\n"</script>
2098<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class="minibutton ok" onclick="javascript: 
2099function time() {
2100  return `The time is ${new Date().toLocaleTimeString()}`;
2101}
2102;
2103
2104;alert(time());">run: time()</div><br class='clear' /></div>
2105    <span class="bookmark" id="switch"></span>
2106      <h2>Switch/When/Else</h2>
2107<p><strong>Switch</strong> statements in JavaScript are a bit awkward. You need to remember to <strong>break</strong> at the end of every <strong>case</strong> statement to avoid accidentally falling through to the default case. CoffeeScript prevents accidental fall-through, and can convert the <code>switch</code> into a returnable, assignable expression. The format is: <code>switch</code> condition, <code>when</code> clauses, <code>else</code> the default case.</p>
2108<p>As in Ruby, <strong>switch</strong> statements in CoffeeScript can take multiple values for each <strong>when</strong> clause. If any of the values match, the clause runs.</p>
2109<div class='code'><pre><code><span class="keyword">switch</span> day
2110  <span class="keyword">when</span> <span class="string">"Mon"</span> <span class="keyword">then</span> go work
2111  <span class="keyword">when</span> <span class="string">"Tue"</span> <span class="keyword">then</span> go relax
2112  <span class="keyword">when</span> <span class="string">"Thu"</span> <span class="keyword">then</span> go iceFishing
2113  <span class="keyword">when</span> <span class="string">"Fri"</span>, <span class="string">"Sat"</span>
2114    <span class="keyword">if</span> day <span class="keyword">is</span> bingoDay
2115      go bingo
2116      go dancing
2117  <span class="keyword">when</span> <span class="string">"Sun"</span> <span class="keyword">then</span> go church
2118  <span class="keyword">else</span> go work
2119</code></pre><pre><code><span class="keyword">switch</span> (day) {
2120  <span class="keyword">case</span> <span class="string">"Mon"</span>:
2121    go(work);
2122    <span class="keyword">break</span>;
2123  <span class="keyword">case</span> <span class="string">"Tue"</span>:
2124    go(relax);
2125    <span class="keyword">break</span>;
2126  <span class="keyword">case</span> <span class="string">"Thu"</span>:
2127    go(iceFishing);
2128    <span class="keyword">break</span>;
2129  <span class="keyword">case</span> <span class="string">"Fri"</span>:
2130  <span class="keyword">case</span> <span class="string">"Sat"</span>:
2131    <span class="keyword">if</span> (day === bingoDay) {
2132      go(bingo);
2133      go(dancing);
2134    }
2135    <span class="keyword">break</span>;
2136  <span class="keyword">case</span> <span class="string">"Sun"</span>:
2137    go(church);
2138    <span class="keyword">break</span>;
2139  <span class="keyword">default</span>:
2140    go(work);
2141}
2142</code></pre>
2142<script>window.example1 = "switch day\n  when \"Mon\" then go work\n  when \"Tue\" then go relax\n  when \"Thu\" then go iceFishing\n  when \"Fri\", \"Sat\"\n    if day is bingoDay\n      go bingo\n      go dancing\n  when \"Sun\" then go church\n  else go work\n"</script>
2142<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><p>Switch statements can also be used without a control expression, turning them in to a cleaner alternative to if/else chains.</p>
2143<div class='code'><pre><code>score = <span class="number">76</span>
2144grade = <span class="keyword">switch</span>
2145  <span class="keyword">when</span> score &lt; <span class="number">60</span> <span class="keyword">then</span> <span class="string">'F'</span>
2146  <span class="keyword">when</span> score &lt; <span class="number">70</span> <span class="keyword">then</span> <span class="string">'D'</span>
2147  <span class="keyword">when</span> score &lt; <span class="number">80</span> <span class="keyword">then</span> <span class="string">'C'</span>
2148  <span class="keyword">when</span> score &lt; <span class="number">90</span> <span class="keyword">then</span> <span class="string">'B'</span>
2149  <span class="keyword">else</span> <span class="string">'A'</span>
2150<span class="comment"># grade == 'C'</span>
2151</code></pre><pre><code><span class="keyword">var</span> grade, score;
2152
2153score = <span class="number">76</span>;
2154
2155grade = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>
2155) </span>{
2156  <span class="keyword">switch</span> (<span class="literal">false</span>) {
2157    <span class="keyword">case</span> !(score &lt; <span class="number">60</span>):
2158      <span class="keyword">return</span> <span class="string">'F'</span>;
2159    <span class="keyword">case</span> !(score &lt; <span class="number">70</span>):
2160      <span class="keyword">return</span> <span class="string">'D'</span>;
2161    <span class="keyword">case</span> !(score &lt; <span class="number">80</span>):
2162      <span class="keyword">return</span> <span class="string">'C'</span>;
2163    <span class="keyword">case</span> !(score &lt; <span class="number">90</span>):
2164      <span class="keyword">return</span> <span class="string">'B'</span>;
2165    <span class="keyword">default</span>:
2166      <span class="keyword">return</span> <span class="string">'A'</span>;
2167  }
2168})();
2169</code></pre>
2169<script>window.example2 = "score = 76\ngrade = switch\n  when score < 60 then 'F'\n  when score < 70 then 'D'\n  when score < 80 then 'C'\n  when score < 90 then 'B'\n  else 'A'\n# grade == 'C'\n"</script>
2169<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><br class='clear' /></div>
2170    <span class="bookmark" id="try-catch"></span>
2171      <h2>Try/Catch/Finally</h2>
2172<p>Try-expressions have the same semantics as try-statements in JavaScript, though in CoffeeScript, you may omit <em>both</em> the catch and finally parts. The catch part may also omit the error parameter if it is not needed.</p>
2173<div class='code'><pre><code><span class="keyword">try</span>
2174  allHellBreaksLoose()
2175  catsAndDogsLivingTogether()
2176<span class="keyword">catch</span> error
2177  <span class="built_in">print</span> error
2178<span class="keyword">finally</span>
2179  cleanUp()
2180</code></pre><pre><code><span class="keyword">var</span> error;
2181
2182<span class="keyword">try</span> {
2183  allHellBreaksLoose();
2184  catsAndDogsLivingTogether();
2185} <span class="keyword">catch</span> (error1) {
2186  error = error1;
2187  print(error);
2188} <span class="keyword">finally</span> {
2189  cleanUp();
2190}
2191</code></pre>
2191<script>window.example1 = "try\n  allHellBreaksLoose()\n  catsAndDogsLivingTogether()\ncatch error\n  print error\nfinally\n  cleanUp()\n"</script>
2191<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div>
2192    <span class="bookmark" id="comparisons"></span>
2193      <h2>Chained Comparisons</h2>
2194<p>CoffeeScript borrows <a href="https://docs.python.org/3/reference/expressions.html#not-in">chained comparisons</a> from Python — making it easy to test if a value falls within a certain range.</p>
2195<div class='code'><pre><code>cholesterol = <span class="number">127</span>
2196
2197healthy = <span class="number">200</span> &gt; cholesterol &gt; <span class="number">60</span>
2198</code></pre><pre><code><span class="keyword">var</span> cholesterol, healthy;
2199
2200cholesterol = <span class="number">127</span>;
2201
2202healthy = (<span class="number">200</span> &gt; cholesterol &amp;&amp; cholesterol &gt; <span class="number">60</span>);
2203</code></pre>
2203<script>window.example1 = "cholesterol = 127\n\nhealthy = 200 > cholesterol > 60\n"</script>
2203<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var cholesterol, healthy;
2204
2205cholesterol = 127;
2206
2207healthy = (200 > cholesterol && cholesterol > 60);
2208;alert(healthy);">run: healthy</div><br class='clear' /></div>
2209    <span class="bookmark" id="strings"></span>
2210      <h2>String Interpolation, Block Strings, and Block Comments</h2>
2211<p>Ruby-style string interpolation is included in CoffeeScript. Double-quoted strings allow for interpolated values, using <code>#{ … }</code>, and single-quoted strings are literal. You may even use interpolation in object keys.</p>
2212<div class='code'><pre><code>author = <span class="string">"Wittgenstein"</span>
2213quote  = <span class="string">"A picture is a fact. -- <span class="subst">#{ author }</span>"</span>
2214
2215sentence = <span class="string">"<span class="subst">#{ <span class="number">22</span> / <span class="number">7</span> }</span> is a decent approximation of π"</span>
2216</code></pre><pre><code><span class="keyword">var</span> author, quote, sentence;
2217
2218author = <span class="string">"Wittgenstein"</span>;
2219
2220quote = <span class="string">"A picture is a fact. -- "</span> + author;
2221
2222sentence = (<span class="number">22</span> / <span class="number">7</span>) + <span class="string">" is a decent approximation of π"</span>;
2223</code></pre>
2223<script>window.example1 = "author = \"Wittgenstein\"\nquote  = \"A picture is a fact. -- #{ author }\"\n\nsentence = \"#{ 22 / 7 } is a decent approximation of π\"\n"</script>
2223<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var author, quote, sentence;
2224
2225author = &quot;Wittgenstein&quot;;
2226
2227quote = &quot;A picture is a fact. -- &quot; + author;
2228
2229sentence = (22 / 7) + &quot; is a decent approximation of π&quot;;
2230;alert(sentence);">run: sentence</div><br class='clear' /></div><p>Multiline strings are allowed in CoffeeScript. Lines are joined by a single space unless they end with a backslash. Indentation is ignored.</p>
2231<div class='code'><pre><code>mobyDick = <span class="string">"Call me Ishmael. Some years ago --
2232  never mind how long precisely -- having little
2233  or no money in my purse, and nothing particular
2234  to interest me on shore, I thought I would sail
2235  about a little and see the watery part of the
2236  world..."</span>
2237</code></pre><pre><code><span class="keyword">var</span> mobyDick;
2238
2239mobyDick = <span class="string">"Call me Ishmael. Some years ago -- never mind how long precisely -- having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world..."</span>;
2240</code></pre>
2240<script>window.example2 = "mobyDick = \"Call me Ishmael. Some years ago --\n  never mind how long precisely -- having little\n  or no money in my purse, and nothing particular\n  to interest me on shore, I thought I would sail\n  about a little and see the watery part of the\n  world...\"\n"</script>
2240<div class='minibutton load' onclick='javascript: loadConsole(example2);'>load</div><div class="minibutton ok" onclick="javascript: var mobyDick;
2241
2242mobyDick = &quot;Call me Ishmael. Some years ago -- never mind how long precisely -- having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world...&quot;;
2243;alert(mobyDick);">run: mobyDick</div><br class='clear' /></div><p>Block strings can be used to hold formatted or indentation-sensitive text (or, if you just don’t feel like escaping quotes and apostrophes). The indentation level that begins the block is maintained throughout, so you can keep it all aligned with the body of your code.</p>
2244<div class='code'><pre><code>html = <span class="string">"""
2245       &lt;strong&gt;
2246         cup of coffeescript
2247       &lt;/strong&gt;
2248       """</span>
2249</code></pre><pre><code><span class="keyword">var</span> html;
2250
2251html = <span class="string">"&lt;strong&gt;\n  cup of coffeescript\n&lt;/strong&gt;"</span>;
2252</code></pre>
2252<script>window.example3 = "html = \"\"\"\n       <strong>\n         cup of coffeescript\n       </strong>\n       \"\"\"\n"</script>
2252<div class='minibutton load' onclick='javascript: loadConsole(example3);'>load</div><div class="minibutton ok" onclick="javascript: var html;
2253
2254html = &quot;<strong>\n  cup of coffeescript\n</strong>&quot;;
2255;alert(html);">run: html</div><br class='clear' /></div><p>Double-quoted block strings, like other double-quoted strings, allow interpolation.</p>
2256<p>Sometimes you’d like to pass a block comment through to the generated JavaScript. For example, when you need to embed a licensing header at the top of a file. Block comments, which mirror the syntax for block strings, are preserved in the generated code.</p>
2257<div class='code'><pre><code><span class="comment">###
2258SkinnyMochaHalfCaffScript Compiler v1.0
2259Released under the MIT License
2260###</span>
2261</code></pre><pre><code>
2262<span class="comment">/*
2263SkinnyMochaHalfCaffScript Compiler v1.0
2264Released under the MIT License
2265 */</span>
2266
2267</code></pre>
2267<script>window.example4 = "###\nSkinnyMochaHalfCaffScript Compiler v1.0\nReleased under the MIT License\n###\n"</script>
2267<div class='minibutton load' onclick='javascript: loadConsole(example4);'>load</div><br class='clear' /></div>
2268    <span class="bookmark" id="tagged-template-literals"></span>
2269      <h2>Tagged Template Literals</h2>
2270<p>CoffeeScript supports <a href="https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Template_literals#Tagged_template_literals">ES2015 tagged template literals</a>, which enable customized string interpolation. If you immediately prefix a string with a function name (no space between the two), CoffeeScript will output this “function plus string” combination as an ES2015 tagged template literal, which will <a href="https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Template_literals#Tagged_template_literals">behave accordingly</a>: the function is called, with the parameters being the input text and expression parts that make up the interpolated string. The function can then assemble these parts into an output string, providing custom string interpolation.</p>
2271<p>Be aware that the CoffeeScript compiler is outputting ES2015 syntax for this feature, so your target JavaScript runtime(s) must support this syntax for your code to work; or you could use tools like <a href="http://babeljs.io/">Babel</a> or <a href="https://github.com/google/traceur-compiler">Traceur Compiler</a> to convert this ES2015 syntax into compatible JavaScript.</p>
2272<div class='code'><pre><code><span class="function"><span class="title">upperCaseExpr</span> = <span class="params">(textParts, expressions...)</span> -&gt;</span>
2273  textParts.reduce (text, textPart, i) -&gt;
2274    text + expressions[i - <span class="number">1</span>].toUpperCase() + textPart
2275<span class="function">
2276<span class="title">greet</span> = <span class="params">(name, adjective)</span> -&gt;</span>
2277  upperCaseExpr<span class="string">"""
2278               Hi <span class="subst">#{name}</span>. You look <span class="subst">#{adjective}</span>!
2279               """</span>
2280</code></pre><pre><code><span class="keyword">var</span> greet, upperCaseExpr,
2281  slice = [].slice;
2282
2283upperCaseExpr = <span class="function"><span class="keyword">function</span>(<span class="params"></span>
2283) </span>{
2284  <span class="keyword">var</span> expressions, textParts;
2285  textParts = <span class="built_in">arguments</span>[<span class="number">0</span>], expressions = <span class="number">2</span> &lt;= <span class="built_in">arguments</span>.length ? slice.call(<span class="built_in">arguments</span>, <span class="number">1</span>) : [];
2286  <span class="keyword">return</span> textParts.reduce(<span class="function"><span class="keyword">function</span>(<span class="params">text, textPart, i</span>) </span>{
2287    <span class="keyword">return</span> text + expressions[i - <span class="number">1</span>].toUpperCase() + textPart;
2288  });
2289};
2290
2291greet = <span class="function"><span class="keyword">function</span>(<span class="params">name, adjective</span>) </span>{
2292  <span class="keyword">return</span> upperCaseExpr<span class="string">`Hi <span class="subst">${name}</span>. You look <span class="subst">${adjective}</span>!`</span>;
2293};
2294</code></pre>
2294<script>window.example1 = "upperCaseExpr = (textParts, expressions...) ->\n  textParts.reduce (text, textPart, i) ->\n    text + expressions[i - 1].toUpperCase() + textPart\n\ngreet = (name, adjective) ->\n  upperCaseExpr\"\"\"\n               Hi #{name}. You look #{adjective}!\n               \"\"\"\n"</script>
2294<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><div class="minibutton ok" onclick="javascript: var greet, upperCaseExpr,
2295  slice = [].slice;
2296
2297upperCaseExpr = function() {
2298  var expressions, textParts;
2299  textParts = arguments[0], expressions = 2 <= arguments.length ? slice.call(arguments, 1) : [];
2300  return textParts.reduce(function(text, textPart, i) {
2301    return text + expressions[i - 1].toUpperCase() + textPart;
2302  });
2303};
2304
2305greet = function(name, adjective) {
2306  return upperCaseExpr`Hi ${name}. You look ${adjective}!`;
2307};
2308;alert(greet(&quot;greg&quot;, &quot;awesome&quot;));">run: greet("greg", "awesome")</div><br class='clear' /></div>
2309    <span class="bookmark" id="regexes"></span>
2310      <h2>Block Regular Expressions</h2>
2311<p>Similar to block strings and comments, CoffeeScript supports block regexes — extended regular expressions that ignore internal whitespace and can contain comments and interpolation. Modeled after Perl’s <code>/x</code> modifier, CoffeeScript’s block regexes are delimited by <code>///</code> and go a long way towards making complex regular expressions readable. To quote from the CoffeeScript source:</p>
2312<div class='code'><pre><code>OPERATOR = <span class="regexp">/// ^ (
2313  ?: [-=]&gt;             <span class="comment"># function</span>
2314   | [-+*/%&lt;&gt;&amp;|^!?=]=  <span class="comment"># compound assign / compare</span>
2315   | &gt;&gt;&gt;=?             <span class="comment"># zero-fill right shift</span>
2316   | ([-+:])\1         <span class="comment"># doubles</span>
2317   | ([&amp;|&lt;&gt;])\2=?      <span class="comment"># logic / shift</span>
2318   | \?\.              <span class="comment"># soak access</span>
2319   | \.{2,3}           <span class="comment"># range or splat</span>
2320) ///</span>
2321</code></pre><pre><code><span class="keyword">var</span> OPERATOR;
2322
2323OPERATOR = <span class="regexp">/^(?:[-=]&gt;|[-+*\/%&lt;&gt;&amp;|^!?=]=|&gt;&gt;&gt;=?|([-+:])\1|([&amp;|&lt;&gt;])\2=?|\?\.|\.{2,3})/</span>;
2324</code></pre>
2324<script>window.example1 = "OPERATOR = /// ^ (\n  ?: [-=]>             # function\n   | [-+*/%<>&|^!?=]=  # compound assign / compare\n   | >>>=?             # zero-fill right shift\n   | ([-+:])\\1         # doubles\n   | ([&|<>])\\2=?      # logic / shift\n   | \\?\\.              # soak access\n   | \\.{2,3}           # range or splat\n) ///\n"</script>
2324<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div>
2325    <span class="bookmark" id="modules"></span>
2326      <h2>Modules</h2>
2327<p>ES2015 modules are supported in CoffeeScript, with very similar <code>import</code> and <code>export</code> syntax:</p>
2328<div class='code'><pre><code><span class="keyword">import</span> <span class="string">'local-file.coffee'</span>
2329<span class="keyword">import</span> <span class="string">'coffeescript'</span>
2330
2331<span class="keyword">import</span> _ <span class="keyword">from</span> <span class="string">'underscore'</span>
2332<span class="keyword">import</span> * <span class="keyword">as</span> underscore <span class="keyword">from</span> <span class="string">'underscore'</span>
2333
2334<span class="keyword">import</span> { now } <span class="keyword">from</span> <span class="string">'underscore'</span>
2335<span class="keyword">import</span> { now <span class="keyword">as</span> currentTimestamp } <span class="keyword">from</span> <span class="string">'underscore'</span>
2336<span class="keyword">import</span> { first, last } <span class="keyword">from</span> <span class="string">'underscore'</span>
2337<span class="keyword">import</span> utilityBelt, { each } <span class="keyword">from</span> <span class="string">'underscore'</span>
2338
2339<span class="keyword">export</span> <span class="keyword">default</span> Math
2340<span class="keyword">export</span> square = <span class="function"><span class="params">(x)</span> -&gt;</span> x * x
2341<span class="keyword">export</span> <span class="class"><span class="keyword">class</span> <span class="title">Mathematics</span></span>
2342  least: <span class="function"><span class="params">(x, y)</span> -&gt;</span> <span class="keyword">if</span> x &lt; y <span class="keyword">then</span> x <span class="keyword">else</span> y
2343
2344<span class="keyword">export</span> { sqrt }
2345<span class="keyword">export</span> { sqrt <span class="keyword">as</span> squareRoot }
2346<span class="keyword">export</span> { Mathematics <span class="keyword">as</span> <span class="keyword">default</span>, sqrt <span class="keyword">as</span> squareRoot }
2347
2348<span class="keyword">export</span> * <span class="keyword">from</span> <span class="string">'underscore'</span>
2349<span class="keyword">export</span> { max, min } <span class="keyword">from</span> <span class="string">'underscore'</span>
2350</code></pre><pre><code><span class="keyword">import</span> <span class="string">'local-file.coffee'</span>;
2351
2352<span class="keyword">import</span> <span class="string">'coffeescript'</span>;
2353
2354<span class="keyword">import</span> _ <span class="keyword">from</span> <span class="string">'underscore'</span>;
2355
2356<span class="keyword">import</span> * <span class="keyword">as</span> underscore <span class="keyword">from</span> <span class="string">'underscore'</span>;
2357
2358<span class="keyword">import</span> {
2359  now
2360} <span class="keyword">from</span> <span class="string">'underscore'</span>;
2361
2362<span class="keyword">import</span> {
2363  now <span class="keyword">as</span> currentTimestamp
2364} <span class="keyword">from</span> <span class="string">'underscore'</span>;
2365
2366<span class="keyword">import</span> {
2367  first,
2368  last
2369} <span class="keyword">from</span> <span class="string">'underscore'</span>;
2370
2371<span class="keyword">import</span> utilityBelt, {
2372  each
2373} <span class="keyword">from</span> <span class="string">'underscore'</span>;
2374
2375<span class="keyword">export</span> <span class="keyword">default</span> <span class="built_in">Math</span>;
2376
2377<span class="keyword">export</span> <span class="keyword">var</span> square = <span class="function"><span class="keyword">function</span>(<span class="params">x</span>
2377) </span>{
2378  <span class="keyword">return</span> x * x;
2379};
2380
2381<span class="keyword">export</span> <span class="keyword">var</span> Mathematics = (<span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{
2382  <span class="function"><span class="keyword">function</span> <span class="title">Mathematics</span>(<span class="params"></span>) </span>{}
2383
2384  Mathematics.prototype.least = <span class="function"><span class="keyword">function</span>(<span class="params">x, y</span>) </span>{
2385    <span class="keyword">if</span> (x &lt; y) {
2386      <span class="keyword">return</span> x;
2387    } <span class="keyword">else</span> {
2388      <span class="keyword">return</span> y;
2389    }
2390  };
2391
2392  <span class="keyword">return</span> Mathematics;
2393
2394})();
2395
2396<span class="keyword">export</span> {
2397  sqrt
2398};
2399
2400<span class="keyword">export</span> {
2401  sqrt <span class="keyword">as</span> squareRoot
2402};
2403
2404<span class="keyword">export</span> {
2405  Mathematics <span class="keyword">as</span> <span class="keyword">default</span>,
2406  sqrt <span class="keyword">as</span> squareRoot
2407};
2408
2409<span class="keyword">export</span> * <span class="keyword">from</span> <span class="string">'underscore'</span>;
2410
2411<span class="keyword">export</span> {
2412  max,
2413  min
2414} <span class="keyword">from</span> <span class="string">'underscore'</span>;
2415</code></pre>
2415<script>window.example1 = "import 'local-file.coffee'\nimport 'coffeescript'\n\nimport _ from 'underscore'\nimport * as underscore from 'underscore'\n\nimport { now } from 'underscore'\nimport { now as currentTimestamp } from 'underscore'\nimport { first, last } from 'underscore'\nimport utilityBelt, { each } from 'underscore'\n\nexport default Math\nexport square = (x) -> x * x\nexport class Mathematics\n  least: (x, y) -> if x < y then x else y\n\nexport { sqrt }\nexport { sqrt as squareRoot }\nexport { Mathematics as default, sqrt as squareRoot }\n\nexport * from 'underscore'\nexport { max, min } from 'underscore'\n"</script>
2415<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><div id="modules-note" class="bookmark"></div>
2416<p>Note that the CoffeeScript compiler <strong>does not resolve modules</strong>; writing an <code>import</code> or <code>export</code> statement in CoffeeScript will produce an <code>import</code> or <code>export</code> statement in the resulting output. It is your responsibility attach another transpiler, such as <a href="https://github.com/google/traceur-compiler">Traceur Compiler</a>, <a href="http://babeljs.io/">Babel</a> or <a href="https://github.com/rollup/rollup">Rollup</a>, to convert this ES2015 syntax into code that will work in your target runtimes.</p>
2417<p>Also note that any file with an <code>import</code> or <code>export</code> statement will be output without a <a href="#lexical-scope">top-level function safety wrapper</a>; in other words, importing or exporting modules will automatically trigger <a href="#usage">bare</a> mode for that file. This is because per the ES2015 spec, <code>import</code> or <code>export</code> statements must occur at the topmost scope.</p>
2418
2419  <span class="bookmark" id="cake"></span>
2420    <h2>Cake, and Cakefiles</h2>
2421<p>CoffeeScript includes a (very) simple build system similar to <a href="http://www.gnu.org/software/make/">Make</a> and <a href="http://rake.rubyforge.org/">Rake</a>. Naturally, it’s called Cake, and is used for the tasks that build and test the CoffeeScript language itself. Tasks are defined in a file named <code>Cakefile</code>, and can be invoked by running <code>cake [task]</code> from within the directory. To print a list of all the tasks and options, just type <code>cake</code>.</p>
2422<p>Task definitions are written in CoffeeScript, so you can put arbitrary code in your Cakefile. Define a task with a name, a long description, and the function to invoke when the task is run. If your task takes a command-line option, you can define the option with short and long flags, and it will be made available in the <code>options</code> object. Here’s a task that uses the Node.js API to rebuild CoffeeScript’s parser:</p>
2423<div class='code'><pre><code>fs = <span class="built_in">require</span> <span class="string">'fs'</span>
2424
2425option <span class="string">'-o'</span>, <span class="string">'--output [DIR]'</span>, <span class="string">'directory for compiled code'</span>
2426
2427task <span class="string">'build:parser'</span>, <span class="string">'rebuild the Jison parser'</span>, <span class="function"><span class="params">(options)</span> -&gt;</span>
2428  <span class="built_in">require</span> <span class="string">'jison'</span>
2429  code = <span class="built_in">require</span>(<span class="string">'./lib/grammar'</span>).parser.generate()
2430  dir  = options.output <span class="keyword">or</span> <span class="string">'lib'</span>
2431  fs.writeFile <span class="string">"<span class="subst">#{dir}</span>/parser.js"</span>, code
2432</code></pre><pre><code><span class="keyword">var</span> fs;
2433
2434fs = <span class="built_in">require</span>(<span class="string">'fs'</span>);
2435
2436option(<span class="string">'-o'</span>, <span class="string">'--output [DIR]'</span>, <span class="string">'directory for compiled code'</span>);
2437
2438task(<span class="string">'build:parser'</span>, <span class="string">'rebuild the Jison parser'</span>, <span class="function"><span class="keyword">function</span>(<span class="params">options</span>
2438) </span>{
2439  <span class="keyword">var</span> code, dir;
2440  <span class="built_in">require</span>(<span class="string">'jison'</span>);
2441  code = <span class="built_in">require</span>(<span class="string">'./lib/grammar'</span>).parser.generate();
2442  dir = options.output || <span class="string">'lib'</span>;
2443  <span class="keyword">return</span> fs.writeFile(dir + <span class="string">"/parser.js"</span>, code);
2444});
2445</code></pre>
2445<script>window.example1 = "fs = require 'fs'\n\noption '-o', '--output [DIR]', 'directory for compiled code'\n\ntask 'build:parser', 'rebuild the Jison parser', (options) ->\n  require 'jison'\n  code = require('./lib/grammar').parser.generate()\n  dir  = options.output or 'lib'\n  fs.writeFile \"#{dir}/parser.js\", code\n"</script>
2445<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><p>If you need to invoke one task before another — for example, running <code>build</code> before <code>test</code>, you can use the <code>invoke</code> function: <code>invoke 'build'</code>. Cake tasks are a minimal way to expose your CoffeeScript functions to the command line, so <a href="annotated-source/cake.html">don’t expect any fanciness built-in</a>. If you need dependencies, or async callbacks, it’s best to put them in your code itself — not the cake task.</p>
2446
2447  <span class="bookmark" id="source-maps"></span>
2448    <h2>Source Maps</h2>
2449<p>CoffeeScript 1.6.1 and above include support for generating source maps, a way to tell your JavaScript engine what part of your CoffeeScript program matches up with the code being evaluated. Browsers that support it can automatically use source maps to show your original source code in the debugger. To generate source maps alongside your JavaScript files, pass the <code>--map</code> or <code>-m</code> flag to the compiler.</p>
2450<p>For a full introduction to source maps, how they work, and how to hook them up in your browser, read the <a href="https://www.html5rocks.com/en/tutorials/developertools/sourcemaps/">HTML5 Tutorial</a>.</p>
2451
2452  <span class="bookmark" id="scripts"></span>
2453    <h2>“text/coffeescript” Script Tags</h2>
2454<p>While it’s not recommended for serious use, CoffeeScripts may be included directly within the browser using <code>&lt;script type=&quot;text/coffeescript&quot;&gt;</code> tags. The source includes a compressed and minified version of the compiler (<a href="browser-compiler/coffee-script.js">Download current version here, 51k when gzipped</a>) as <code>docs/v1/browser-compiler/coffee-script.js</code>. Include this file on a page with inline CoffeeScript tags, and it will compile and evaluate them in order.</p>
2455<p>In fact, the little bit of glue script that runs “Try CoffeeScript” above, as well as the jQuery for the menu, is implemented in just this way. View source and look at the bottom of the page to see the example. Including the script also gives you access to <code>CoffeeScript.compile()</code> so you can pop open Firebug and try compiling some strings.</p>
2456<p>The usual caveats about CoffeeScript apply — your inline scripts will run within a closure wrapper, so if you want to expose global variables or functions, attach them to the <code>window</code> object.</p>
2457
2458  <span class="bookmark" id="resources"></span>
2459    <h2>Books</h2>
2460<p>There are a number of excellent resources to help you get started with CoffeeScript, some of which are freely available online.</p>
2461<ul>
2462<li><a href="http://arcturo.github.io/library/coffeescript/">The Little Book on CoffeeScript</a> is a brief 5-chapter introduction to CoffeeScript, written with great clarity and precision by <a href="http://alexmaccaw.co.uk/">Alex MacCaw</a>.</li>
2463<li><a href="http://autotelicum.github.io/Smooth-CoffeeScript/">Smooth CoffeeScript</a> is a reimagination of the excellent book <a href="http://eloquentjavascript.net/">Eloquent JavaScript</a>, as if it had been written in CoffeeScript instead. Covers language features as well as the functional and object oriented programming styles. By <a href="https://github.com/autotelicum">E. Hoigaard</a>.</li>
2464<li><a href="http://pragprog.com/book/tbcoffee/coffeescript">CoffeeScript: Accelerated JavaScript Development</a> is <a href="http://trevorburnham.com/">Trevor Burnham</a>’s thorough introduction to the language. By the end of the book, you’ll have built a fast-paced multiplayer word game, writing both the client-side and Node.js portions in CoffeeScript.</li>
2465<li><a href="https://www.packtpub.com/web-development/coffeescript-programming-jquery-rails-and-nodejs">CoffeeScript Programming with jQuery, Rails, and Node.js</a> is a new book by Michael Erasmus that covers CoffeeScript with an eye towards real-world usage both in the browser (jQuery) and on the server-side (Rails, Node).</li>
2466<li><a href="https://leanpub.com/coffeescript-ristretto/read">CoffeeScript Ristretto</a> is a deep dive into CoffeeScript’s semantics from simple functions up through closures, higher-order functions, objects, classes, combinators, and decorators. By <a href="http://braythwayt.com/">Reg Braithwaite</a>.</li>
2467<li><a href="https://efendibooks.com/minibooks/testing-with-coffeescript">Testing with CoffeeScript</a> is a succinct and freely downloadable guide to building testable applications with CoffeeScript and Jasmine.</li>
2468<li><a href="https://www.packtpub.com/web-development/coffeescript-application-development">CoffeeScript Application Development</a> from Packt, introduces CoffeeScript while walking through the process of building a demonstration web application. A <a href="https://www.packtpub.com/web-development/coffeescript-application-development-cookbook">CoffeeScript Application Development Coookbook</a> with over 90 “recipes” is also available.</li>
2469<li><a href="https://www.manning.com/books/coffeescript-in-action">CoffeeScript in Action</a> from Manning Publications, covers CoffeeScript syntax, composition techniques and application development.</li>
2470<li><a href="https://www.dpunkt.de/buecher/4021/coffeescript.html">CoffeeScript: Die Alternative zu JavaScript</a> from dpunkt.verlag, is the first CoffeeScript book in Deutsch.</li>
2471</ul>
2472
2473  <span class="bookmark" id="screencasts"></span>
2474    <h2>Screencasts</h2>
2475<ul>
2476<li><a href="http://coffeescript.codeschool.com/">A Sip of CoffeeScript</a> is a <a href="https://www.codeschool.com">Code School Course</a> which combines 6 screencasts with in-browser coding to make learning fun. The first level is free to try out.</li>
2477<li><a href="https://www.pluralsight.com/courses/meet-coffeescript">Meet CoffeeScript</a> is a 75-minute long screencast by PeepCode, now <a href="https://www.pluralsight.com/">PluralSight</a>. Highly memorable for its animations which demonstrate transforming CoffeeScript into the equivalent JS.</li>
2478<li>If you’re looking for less of a time commitment, RailsCasts’ <a href="http://railscasts.com/episodes/267-coffeescript-basics">CoffeeScript Basics</a> should have you covered, hitting all of the important notes about CoffeeScript in 11 minutes.</li>
2479</ul>
2480
2481  <span class="bookmark" id="examples"></span>
2482    <h2>Examples</h2>
2483<p>The <a href="https://github.com/trending?l=coffeescript&amp;since=monthly">best list of open-source CoffeeScript examples</a> can be found on GitHub. But just to throw out a few more:</p>
2484<ul>
2485<li><strong>GitHub</strong>’s <a href="https://hubot.github.com/">Hubot</a>, a friendly IRC robot that can perform any number of useful and useless tasks.</li>
2486<li><strong>sstephenson</strong>’s <a href="http://pow.cx/">Pow</a>, a zero-configuration Rack server, with comprehensive annotated source.</li>
2487<li><strong>technoweenie</strong>’s <a href="https://github.com/technoweenie/coffee-resque">Coffee-Resque</a>, a port of <a href="https://github.com/defunkt/resque">Resque</a> for Node.js.</li>
2488<li><strong>stephank</strong>’s <a href="https://github.com/stephank/orona">Orona</a>, a remake of the Bolo tank game for modern browsers.</li>
2489<li><strong>GitHub</strong>’s <a href="https://atom.io/">Atom</a>, a hackable text editor built on web technologies.</li>
2490<li><strong>Basecamp</strong>’s <a href="https://trix-editor.org/">Trix</a>, a rich text editor for web apps.</li>
2491</ul>
2492
2493  <span class="bookmark" id="additional-resources"></span>
2494    <h2>Resources</h2>
2495<ul>
2496<li>
2497<p><a href="https://github.com/jashkenas/coffeescript/">Source Code</a><br>
2498Use <code>bin/coffee</code> to test your changes,<br>
2499<code>bin/cake test</code> to run the test suite,<br>
2500<code>bin/cake build</code> to rebuild the full CoffeeScript compiler, and<br>
2501<code>bin/cake build:except-parser</code> to recompile much faster if you’re not editing <code>grammar.coffee</code>.</p>
2502<p><code>git checkout lib &amp;&amp; bin/cake build:full</code> is a good command to run when you’re working on the core language. It’ll refresh the <code>lib</code> folder (in case you broke something), build your altered compiler, use that to rebuild itself (a good sanity test) and then run all of the tests. If they pass, there’s a good chance you’ve made a successful change.</p>
2503</li>
2504<li>
2505<p><a href="test.html">Browser Tests</a><br>
2506Run CoffeeScript’s test suite in your current browser.</p>
2507</li>
2508<li>
2509<p><a href="https://github.com/jashkenas/coffeescript/issues">CoffeeScript Issues</a><br>
2510Bug reports, feature proposals, and ideas for changes to the language belong here.</p>
2511</li>
2512<li>
2513<p><a href="https://groups.google.com/forum/#!forum/coffeescript">CoffeeScript Google Group</a><br>
2514If you’d like to ask a question, the mailing list is a good place to get help.</p>
2515</li>
2516<li>
2517<p><a href="https://github.com/jashkenas/coffeescript/wiki">The CoffeeScript Wiki</a><br>
2518If you’ve ever learned a neat CoffeeScript tip or trick, or ran into a gotcha — share it on the wiki. The wiki also serves as a directory of handy <a href="https://github.com/jashkenas/coffeescript/wiki/Text-editor-plugins">text editor extensions</a>, <a href="https://github.com/jashkenas/coffeescript/wiki/Web-framework-plugins">web framework plugins</a>, and general <a href="https://github.com/jashkenas/coffeescript/wiki/Build-tools">CoffeeScript build tools</a>.</p>
2519</li>
2520<li>
2521<p><a href="https://github.com/jashkenas/coffeescript/wiki/FAQ">The FAQ</a><br>
2522Perhaps your CoffeeScript-related question has been asked before. Check the FAQ first.</p>
2523</li>
2524<li>
2525<p><a href="http://js2coffee.org">JS2Coffee</a><br>
2526Is a very well done reverse JavaScript-to-CoffeeScript compiler. It’s not going to be perfect (infer what your JavaScript classes are, when you need bound functions, and so on…) — but it’s a great starting point for converting simple scripts.</p>
2527</li>
2528<li>
2529<p><a href="https://github.com/jashkenas/coffeescript/tree/master/documentation/images">High-Rez Logo</a><br>
2530The CoffeeScript logo is available in SVG for use in presentations.</p>
2531</li>
2532</ul>
2533
2534  <span class="bookmark" id="chat"></span>
2535    <h2>Web Chat (IRC)</h2>
2536<p>Quick help and advice can usually be found in the CoffeeScript IRC room. Join <code>#coffeescript</code> on <code>irc.freenode.net</code>, or click the button below to open a webchat session on this page.</p>
2537<p><button id="open_webchat">click to open #coffeescript</button></p>
2538
2539  <span class="bookmark" id="changelog"></span>
2540    <h2>Change Log</h2>
2541<div class="anchor" id="1.12.7"></div>
2542<h2 class="header">
2543  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.6...1.12.7">1.12.7</a>
2544  <span class="timestamp"> &mdash; <time datetime="2017-07-16">July 16, 2017</time></span>
2545</h2><ul>
2546<li>Fix regressions in 1.12.6 related to chained function calls and indented <code>return</code> and <code>throw</code> arguments.</li>
2547<li>The REPL no longer warns about assigning to <code>_</code>.</li>
2548</ul>
2549<div class="anchor" id="1.12.6"></div>
2550<h2 class="header">
2551  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.5...1.12.6">1.12.6</a>
2552  <span class="timestamp"> &mdash; <time datetime="2017-05-15">May 15, 2017</time></span>
2553</h2><ul>
2554<li>The <code>return</code> and <code>export</code> keywords can now accept implicit objects (defined by indentation, without needing braces).</li>
2555<li>Support Unicode code point escapes (e.g. <code>\u{1F4A9}</code>).</li>
2556<li>The <code>coffee</code> command now first looks to see if CoffeeScript is installed under <code>node_modules</code> in the current folder, and executes the <code>coffee</code> binary there if so; or otherwise it runs the globally installed one. This allows you to have one version of CoffeeScript installed globally and a different one installed locally for a particular project. (Likewise for the <code>cake</code> command.)</li>
2557<li>Bugfixes for chained function calls not closing implicit objects or ternaries.</li>
2558<li>Bugfixes for incorrect code generated by the <code>?</code> operator within a termary <code>if</code> statement.</li>
2559<li>Fixed some tests, and failing tests now result in a nonzero exit code.</li>
2560</ul>
2561<div class="anchor" id="1.12.5"></div>
2562<h2 class="header">
2563  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.4...1.12.5">1.12.5</a>
2564  <span class="timestamp"> &mdash; <time datetime="2017-04-10">April 10, 2017</time></span>
2565</h2><ul>
2566<li>Better handling of <code>default</code>, <code>from</code>, <code>as</code> and <code>*</code> within <code>import</code> and <code>export</code> statements. You can now import or export a member named <code>default</code> and the compiler won’t interpret it as the <code>default</code> keyword.</li>
2567<li>Fixed a bug where invalid octal escape sequences weren’t throwing errors in the compiler.</li>
2568</ul>
2569<div class="anchor" id="1.12.4"></div>
2570<h2 class="header">
2571  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.3...1.12.4">1.12.4</a>
2572  <span class="timestamp"> &mdash; <time datetime="2017-02-18">February 18, 2017</time></span>
2573</h2><ul>
2574<li>The <code>cake</code> commands have been updated, with new <code>watch</code> options for most tasks. Clone the <a href="https://github.com/jashkenas/coffeescript">CoffeeScript repo</a> and run <code>cake</code>
2574 at the root of the repo to see the options.</li>
2575<li>Fixed a bug where <code>export</code>ing a referenced variable was preventing the variable from being declared.</li>
2576<li>Fixed a bug where the <code>coffee</code> command wasn’t working for a <code>.litcoffee</code> file.</li>
2577<li>Bugfixes related to tokens and location data, for better source maps and improved compatibility with downstream tools.</li>
2578</ul>
2579<div class="anchor" id="1.12.3"></div>
2580<h2 class="header">
2581  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.2...1.12.3">1.12.3</a>
2582  <span class="timestamp"> &mdash; <time datetime="2017-01-24">January 24, 2017</time></span>
2583</h2><ul>
2584<li><code>@</code> values can now be used as indices in <code>for</code> expressions. This loosens the compilation of <code>for</code> expressions to allow the index variable to be an <code>@</code> value, e.g. <code>do @visit for @node, @index in nodes</code>. Within <code>@visit</code>, the index of the current node (<code>@node</code>) would be available as <code>@index</code>.</li>
2585<li>CoffeeScript’s patched <code>Error.prepareStackTrace</code> has been restored, with some revisions that should prevent the erroneous exceptions that were making life difficult for some downstream projects. This fixes the incorrect line numbers in stack traces since 1.12.2.</li>
2586<li>The <code>//=</code> operator’s output now wraps parentheses around the right operand, like the other assignment operators.</li>
2587</ul>
2588<div class="anchor" id="1.12.2"></div>
2589<h2 class="header">
2590  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.1...1.12.2">1.12.2</a>
2591  <span class="timestamp"> &mdash; <time datetime="2016-12-16">December 16, 2016</time></span>
2592</h2><ul>
2593<li>The browser compiler can once again be built unminified via <code>MINIFY=false cake build:browser</code>.</li>
2594<li>The error-prone patched version of <code>Error.prepareStackTrace</code> has been removed.</li>
2595<li>Command completion in the REPL (pressing tab to get suggestions) has been fixed for Node 6.9.1+.</li>
2596<li>The <a href="test.html">browser-based tests</a> now include all the tests as the Node-based version.</li>
2597</ul>
2598<div class="anchor" id="1.12.1"></div>
2599<h2 class="header">
2600  <a href="https://github.com/jashkenas/coffeescript/compare/1.12.0...1.12.1">1.12.1</a>
2601  <span class="timestamp"> &mdash; <time datetime="2016-12-07">December 7, 2016</time></span>
2602</h2><ul>
2603<li>You can now import a module member named <code>default</code>, e.g. <code>import { default } from 'lib'</code>. Though like in ES2015, you cannot import an entire module and name it <code>default</code> (so <code>import default from 'lib'</code> is not allowed).</li>
2604<li>Fix regression where <code>from</code> as a variable name was breaking <code>for</code> loop declarations. For the record, <code>from</code> is not a reserved word in CoffeeScript; you may use it for variable names. <code>from</code> behaves like a keyword within the context of <code>import</code> and <code>export</code> statements, and in the declaration of a <code>for</code> loop; though you should also be able to use variables named <code>from</code> in those contexts, and the compiler should be able to tell the difference.</li>
2605</ul>
2606<div class="anchor" id="1.12.0"></div>
2607<h2 class="header">
2608  <a href="https://github.com/jashkenas/coffeescript/compare/1.11.1...1.12.0">1.12.0</a>
2609  <span class="timestamp"> &mdash; <time datetime="2016-12-04">December 4, 2016</time></span>
2610</h2><ul>
2611<li>CoffeeScript now supports ES2015 <a href="#tagged-template-literals">tagged template literals</a>. Note that using tagged template literals in your code makes you responsible for ensuring that either your runtime supports tagged template literals or that you transpile the output JavaScript further to a version your target runtime(s) support.</li>
2612<li>CoffeeScript now provides a <a href="#generator-iteration"><code>for…from</code></a> syntax for outputting ES2015 <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of"><code>for…of</code></a>. (Sorry they couldn’t match, but we came up with <code>for…of</code> first for something else.) This allows iterating over generators or any other iterable object. Note that using <code>for…from</code> in your code makes you responsible for ensuring that either your runtime supports <code>for…of</code> or that you transpile the output JavaScript further to a version your target runtime(s) support.</li>
2613<li>Triple backticks (<code>```​</code>) allow the creation of embedded JavaScript blocks where escaping single backticks is not required, which should improve interoperability with ES2015 template literals and with Markdown.</li>
2614<li>Within single-backtick embedded JavaScript, backticks can now be escaped via <code>\`​</code>.</li>
2615<li>The browser tests now run in the browser again, and are accessible <a href="test.html">here</a> if you would like to test your browser.</li>
2616<li>CoffeeScript-only keywords in ES2015 <code>import</code>s and <code>export</code>s are now ignored.</li>
2617<li>The compiler now throws an error on trying to export an anonymous class.</li>
2618<li>Bugfixes related to tokens and location data, for better source maps and improved compatibility with downstream tools.</li>
2619</ul>
2620<div class="anchor" id="1.11.1"></div>
2621<h2 class="header">
2622  <a href="https://github.com/jashkenas/coffeescript/compare/1.11.0...1.11.1">1.11.1</a>
2623  <span class="timestamp"> &mdash; <time datetime="2016-10-02">October 2, 2016</time></span>
2624</h2><ul>
2625<li>Bugfix for shorthand object syntax after interpolated keys.</li>
2626<li>Bugfix for indentation-stripping in <code>&quot;&quot;&quot;</code> strings.</li>
2627<li>Bugfix for not being able to use the name “arguments” for a prototype property of class.</li>
2628<li>Correctly compile large hexadecimal numbers literals to <code>2e308</code> (just like all other large number literals do).</li>
2629</ul>
2630<div class="anchor" id="1.11.0"></div>
2631<h2 class="header">
2632  <a href="https://github.com/jashkenas/coffeescript/compare/1.10.0...1.11.0">1.11.0</a>
2633  <span class="timestamp"> &mdash; <time datetime="2016-09-24">September 24, 2016</time></span>
2634</h2><ul>
2635<li>
2636<p>CoffeeScript now supports ES2015 <a href="#modules"><code>import</code> and <code>export</code> syntax</a>.</p>
2637</li>
2638<li>
2639<p>Added the <code>-M, --inline-map</code> flag to the compiler, allowing you embed the source map directly into the output JavaScript, rather than as a separate file.</p>
2640</li>
2641<li>
2642<p>A bunch of fixes for <code>yield</code>:</p>
2643<ul>
2644<li>
2645<p><code>yield return</code> can no longer mistakenly be used as an expression.</p>
2646</li>
2647<li>
2648<p><code>yield</code> now mirrors <code>return</code> in that it can be used stand-alone as well as with expressions. Where you previously wrote <code>yield undefined</code>
2648, you may now write simply <code>yield</code>. However, this means also inheriting the same syntax limitations that <code>return</code> has, so these examples no longer compile:</p>
2649<blockquote class="uneditable-code-block"><pre><code>doubles = -&gt;
2650  yield for i in [1..3]
2651    i * 2
2652six = -&gt;
2653  yield
2654    2 * 3
2655</code></pre>
2656</blockquote></li>
2657<li>
2658<p>The JavaScript output is a bit nicer, with unnecessary parentheses and spaces, double indentation and double semicolons around <code>yield</code> no longer present.</p>
2659</li>
2660</ul>
2661</li>
2662<li>
2663<p><code>&amp;&amp;=</code>, <code>||=</code>, <code>and=</code> and <code>or=</code> no longer accidentally allow a space before the equals sign.</p>
2664</li>
2665<li>
2666<p>Improved several error messages.</p>
2667</li>
2668<li>
2669<p>Just like <code>undefined</code> compiles to <code>void 0</code>, <code>NaN</code> now compiles into <code>0/0</code> and <code>Infinity</code> into <code>2e308</code>.</p>
2670</li>
2671<li>
2672<p>Bugfix for renamed destructured parameters with defaults. <code>({a: b = 1}) -&gt;</code> no longer crashes the compiler.</p>
2673</li>
2674<li>
2675<p>Improved the internal representation of a CoffeeScript program. This is only noticeable to tools that use <code>CoffeeScript.tokens</code> or <code>CoffeeScript.nodes</code>. Such tools need to update to take account for changed or added tokens and nodes.</p>
2676</li>
2677<li>
2678<p>Several minor bug fixes, including:</p>
2679<ul>
2680<li>The caught error in <code>catch</code> blocks is no longer declared unnecessarily, and no longer mistakenly named <code>undefined</code> for <code>catch</code>-less <code>try</code> blocks.</li>
2681<li>Unassignable parameter destructuring no longer crashes the compiler.</li>
2682<li>Source maps are now used correctly for errors thrown from .coffee.md files.</li>
2683<li><code>coffee -e 'throw null'</code> no longer crashes.</li>
2684<li>The REPL no longer crashes when using <code>.exit</code> to exit it.</li>
2685<li>Invalid JavaScript is no longer output when lots of <code>for</code> loops are used in the same scope.</li>
2686<li>A unicode issue when using stdin with the CLI.</li>
2687</ul>
2688</li>
2689</ul>
2690<div class="anchor" id="1.10.0"></div>
2691<h2 class="header">
2692  <a href="https://github.com/jashkenas/coffeescript/compare/1.9.3...1.10.0">1.10.0</a>
2693  <span class="timestamp"> &mdash; <time datetime="2015-09-03">September 3, 2015</time></span>
2694</h2><ul>
2695<li>
2696<p>CoffeeScript now supports ES2015-style destructuring defaults.</p>
2697</li>
2698<li>
2699<p><code>(offsetHeight: height) -&gt;</code> no longer compiles. That syntax was accidental and partly broken. Use <code>({offsetHeight: height}) -&gt;</code> instead. Object destructuring always requires braces.</p>
2700</li>
2701<li>
2702<p>Several minor bug fixes, including:</p>
2703<ul>
2704<li>A bug where the REPL would sometimes report valid code as invalid, based on what you had typed earlier.</li>
2705<li>A problem with multiple JS contexts in the jest test framework.</li>
2706<li>An error in io.js where strict mode is set on internal modules.</li>
2707<li>A variable name clash for the caught error in <code>catch</code> blocks.</li>
2708</ul>
2709</li>
2710</ul>
2711<div class="anchor" id="1.9.3"></div>
2712<h2 class="header">
2713  <a href="https://github.com/jashkenas/coffeescript/compare/1.9.2...1.9.3">1.9.3</a>
2714  <span class="timestamp"> &mdash; <time datetime="2015-05-27">May 27, 2015</time></span>
2715</h2><ul>
2716<li>Bugfix for interpolation in the first key of an object literal in an implicit call.</li>
2717<li>Fixed broken error messages in the REPL, as well as a few minor bugs with the REPL.</li>
2718<li>Fixed source mappings for tokens at the beginning of lines when compiling with the <code>--bare</code> option. This has the nice side effect of generating smaller source maps.</li>
2719<li>Slight formatting improvement of compiled block comments.</li>
2720<li>Better error messages for <code>on</code>, <code>off</code>, <code>yes</code> and <code>no</code>.</li>
2721</ul>
2722<div class="anchor" id="1.9.2"></div>
2723<h2 class="header">
2724  <a href="https://github.com/jashkenas/coffeescript/compare/1.9.1...1.9.2">1.9.2</a>
2725  <span class="timestamp"> &mdash; <time datetime="2015-04-15">April 15, 2015</time></span>
2726</h2><ul>
2727<li>Fixed a <strong>watch</strong> mode error introduced in 1.9.1 when compiling multiple files with the same filename.</li>
2728<li>Bugfix for <code>yield</code> around expressions containing <code>this</code>.</li>
2729<li>Added a Ruby-style <code>-r</code> option to the REPL, which allows requiring a module before execution with <code>--eval</code> or <code>--interactive</code>.</li>
2730<li>In <code>&lt;script type=&quot;text/coffeescript&quot;&gt;</code> tags, to avoid possible duplicate browser requests for .coffee files, you can now use the <code>data-src</code> attribute instead of <code>src</code>.</li>
2731<li>Minor bug fixes for IE8, strict ES5 regular expressions and Browserify.</li>
2732</ul>
2733<div class="anchor" id="1.9.1"></div>
2734<h2 class="header">
2735  <a href="https://github.com/jashkenas/coffeescript/compare/1.9.0...1.9.1">1.9.1</a>
2736  <span class="timestamp"> &mdash; <time datetime="2015-02-18">February 18, 2015</time></span>
2737</h2><ul>
2738<li>Interpolation now works in object literal keys (again). You can use this to dynamically name properties.</li>
2739<li>
2739Internal compiler variable names no longer start with underscores. This makes the generated JavaScript a bit prettier, and also fixes an issue with the completely broken and ungodly way that AngularJS “parses” function arguments.</li>
2740<li>Fixed a few <code>yield</code>-related edge cases with <code>yield return</code> and <code>yield throw</code>.</li>
2741<li>Minor bug fixes and various improvements to compiler error messages.</li>
2742</ul>
2743<div class="anchor" id="1.9.0"></div>
2744<h2 class="header">
2745  <a href="https://github.com/jashkenas/coffeescript/compare/1.8.0...1.9.0">1.9.0</a>
2746  <span class="timestamp"> &mdash; <time datetime="2015-01-29">January 29, 2015</time></span>
2747</h2><ul>
2748<li>CoffeeScript now supports ES2015 generators. A generator is simply a function that <code>yield</code>s.</li>
2749<li>More robust parsing and improved error messages for strings and regexes — especially with respect to interpolation.</li>
2750<li>Changed strategy for the generation of internal compiler variable names. Note that this means that <code>@example</code> function parameters are no longer available as naked <code>example</code> variables within the function body.</li>
2751<li>Fixed REPL compatibility with latest versions of Node and Io.js.</li>
2752<li>Various minor bug fixes.</li>
2753</ul>
2754<div class="anchor" id="1.8.0"></div>
2755<h2 class="header">
2756  <a href="https://github.com/jashkenas/coffeescript/compare/1.7.1...1.8.0">1.8.0</a>
2757  <span class="timestamp"> &mdash; <time datetime="2014-08-26">August 26, 2014</time></span>
2758</h2><ul>
2759<li>The <code>--join</code> option of the CLI is now deprecated.</li>
2760<li>Source maps now use <code>.js.map</code> as file extension, instead of just <code>.map</code>.</li>
2761<li>The CLI now exits with the exit code 1 when it fails to write a file to disk.</li>
2762<li>The compiler no longer crashes on unterminated, single-quoted strings.</li>
2763<li>Fixed location data for string interpolations, which made source maps out of sync.</li>
2764<li>The error marker in error messages is now correctly positioned if the code is indented with tabs.</li>
2765<li>Fixed a slight formatting error in CoffeeScript’s source map-patched stack traces.</li>
2766<li>The <code>%%</code> operator now coerces its right operand only once.</li>
2767<li>It is now possible to require CoffeeScript files from Cakefiles without having to register the compiler first.</li>
2768<li>The CoffeeScript REPL is now exported and can be required using <code>require 'coffee-script/repl'</code>.</li>
2769<li>Fixes for the REPL in Node 0.11.</li>
2770</ul>
2771<div class="anchor" id="1.7.1"></div>
2772<h2 class="header">
2773  <a href="https://github.com/jashkenas/coffeescript/compare/1.7.0...1.7.1">1.7.1</a>
2774  <span class="timestamp"> &mdash; <time datetime="2014-01-29">January 29, 2014</time></span>
2775</h2><ul>
2776<li>Fixed a typo that broke node module lookup when running a script directly with the <code>coffee</code> binary.</li>
2777</ul>
2778<div class="anchor" id="1.7.0"></div>
2779<h2 class="header">
2780  <a href="https://github.com/jashkenas/coffeescript/compare/1.6.3...1.7.0">1.7.0</a>
2781  <span class="timestamp"> &mdash; <time datetime="2014-01-28">January 28, 2014</time></span>
2782</h2><ul>
2783<li>When requiring CoffeeScript files in Node you must now explicitly register the compiler. This can be done with <code>require 'coffee-script/register'</code> or <code>CoffeeScript.register()</code>. Also for configuration such as Mocha’s, use <strong>coffee-script/register</strong>.</li>
2784<li>Improved error messages, source maps and stack traces. Source maps now use the updated <code>//#</code> syntax.</li>
2785<li>Leading <code>.</code> now closes all open calls, allowing for simpler chaining syntax.</li>
2786</ul>
2787<div class='code'><pre><code>$ <span class="string">'body'</span>
2788.click (e) -&gt;
2789  $ <span class="string">'.box'</span>
2790  .fadeIn <span class="string">'fast'</span>
2791  .addClass <span class="string">'.active'</span>
2792.css <span class="string">'background'</span>, <span class="string">'white'</span>
2793</code></pre><pre><code>$(<span class="string">'body'</span>).click(<span class="function"><span class="keyword">function</span>(<span class="params">e</span>
2793) </span>{
2794  <span class="keyword">return</span> $(<span class="string">'.box'</span>).fadeIn(<span class="string">'fast'</span>).addClass(<span class="string">'.active'</span>);
2795}).css(<span class="string">'background'</span>, <span class="string">'white'</span>);
2796</code></pre>
2796<script>window.example1 = "$ 'body'\n.click (e) ->\n  $ '.box'\n  .fadeIn 'fast'\n  .addClass '.active'\n.css 'background', 'white'\n"</script>
2796<div class='minibutton load' onclick='javascript: loadConsole(example1);'>load</div><br class='clear' /></div><ul>
2797<li>Added <code>**</code>, <code>//</code> and <code>%%</code> operators and <code>...</code> expansion in parameter lists and destructuring expressions.</li>
2798<li>Multiline strings are now joined by a single space and ignore all indentation. A backslash at the end of a line can denote the amount of whitespace between lines, in both strings and heredocs. Backslashes correctly escape whitespace in block regexes.</li>
2799<li>Closing brackets can now be indented and therefore no longer cause unexpected error.</li>
2800<li>Several breaking compilation fixes. Non-callable literals (strings, numbers etc.) don’t compile in a call now and multiple postfix conditionals compile properly. Postfix conditionals and loops always bind object literals. Conditional assignment compiles properly in subexpressions. <code>super</code> is disallowed outside of methods and works correctly inside <code>for</code> loops.</li>
2801<li>Formatting of compiled block comments has been improved.</li>
2802<li>No more <code>-p</code> folders on Windows.</li>
2803<li>The <code>options</code> object passed to CoffeeScript is no longer mutated.</li>
2804</ul>
2805<div class="anchor" id="1.6.3"></div>
2806<h2 class="header">
2807  <a href="https://github.com/jashkenas/coffeescript/compare/1.6.2...1.6.3">1.6.3</a>
2808  <span class="timestamp"> &mdash; <time datetime="2013-06-02">June 2, 2013</time></span>
2809</h2><ul>
2810<li>The CoffeeScript REPL now remembers your history between sessions. Just like a proper REPL should.</li>
2811<li>You can now use <code>require</code> in Node to load <code>.coffee.md</code> Literate CoffeeScript files. In the browser, <code>text/literate-coffeescript</code> script tags.</li>
2812<li>The old <code>coffee --lint</code> command has been removed. It was useful while originally working on the compiler, but has been surpassed by JSHint. You may now use <code>-l</code> to pass literate files in over <strong>stdio</strong>.</li>
2813<li>Bugfixes for Windows path separators, <code>catch</code> without naming the error, and executable-class-bodies-with- prototypal-property-attachment.</li>
2814</ul>
2815<div class="anchor" id="1.6.2"></div>
2816<h2 class="header">
2817  <a href="https://github.com/jashkenas/coffeescript/compare/1.6.1...1.6.2">1.6.2</a>
2818  <span class="timestamp"> &mdash; <time datetime="2013-03-18">March 18, 2013</time></span>
2819</h2><ul>
2820<li>Source maps have been used to provide automatic line-mapping when running CoffeeScript directly via the <code>coffee</code> command, and for automatic line-mapping when running CoffeeScript directly in the browser. Also, to provide better error messages for semantic errors thrown by the compiler — <a href="http://cl.ly/NdOA">with colors, even</a>.</li>
2821<li>Improved support for mixed literate/vanilla-style CoffeeScript projects, and generating source maps for both at the same time.</li>
2822<li>Fixes for <strong>1.6.x</strong> regressions with overriding inherited bound functions, and for Windows file path management.</li>
2823<li>The <code>coffee</code> command can now correctly <code>fork()</code> both <code>.coffee</code> and <code>.js</code> files. (Requires Node.js 0.9+)</li>
2824</ul>
2825<div class="anchor" id="1.6.1"></div>
2826<h2 class="header">
2827  <a href="https://github.com/jashkenas/coffeescript/compare/1.5.0...1.6.1">1.6.1</a>
2828  <span class="timestamp"> &mdash; <time datetime="2013-03-05">March 5, 2013</time></span>
2829</h2><ul>
2830<li>First release of <a href="#source-maps">source maps</a>. Pass the <code>--map</code> flag to the compiler, and off you go. Direct all your thanks over to <a href="https://github.com/jwalton">Jason Walton</a>.</li>
2831<li>Fixed a 1.5.0 regression with multiple implicit calls against an indented implicit object. Combinations of implicit function calls and implicit objects should generally be parsed better now — but it still isn’t good <em>style</em> to nest them too heavily.</li>
2832<li><code>.coffee.md</code> is now also supported as a Literate CoffeeScript file extension, for existing tooling. <code>.litcoffee</code> remains the canonical one.</li>
2833<li>Several minor fixes surrounding member properties, bound methods and <code>super</code> in class declarations.</li>
2834</ul>
2835<div class="anchor" id="1.5.0"></div>
2836<h2 class="header">
2837  <a href="https://github.com/jashkenas/coffeescript/compare/1.4.0...1.5.0">1.5.0</a>
2838  <span class="timestamp"> &mdash; <time datetime="2013-02-25">February 25, 2013</time></span>
2839</h2><ul>
2840<li>First release of <a href="#literate">Literate CoffeeScript</a>.</li>
2841<li>The CoffeeScript REPL is now based on the Node.js REPL, and should work better and more familiarly.</li>
2842<li>Returning explicit values from constructors is now forbidden. If you want to return an arbitrary value, use a function, not a constructor.</li>
2843<li>You can now loop over an array backwards, without having to manually deal with the indexes: <code>for item in list by -1</code></li>
2844<li>Source locations are now preserved in the CoffeeScript AST, although source maps are not yet being emitted.</li>
2845</ul>
2846<div class="anchor" id="1.4.0"></div>
2847<h2 class="header">
2848  <a href="https://github.com/jashkenas/coffeescript/compare/1.3.3...1.4.0">1.4.0</a>
2849  <span class="timestamp"> &mdash; <time datetime="2012-10-23">October 23, 2012</time></span>
2850</h2><ul>
2851<li>The CoffeeScript compiler now strips Microsoft’s UTF-8 BOM if it exists, allowing you to compile BOM-borked source files.</li>
2852<li>Fix Node/compiler deprecation warnings by removing <code>registerExtension</code>, and moving from <code>path.exists</code> to <code>fs.exists</code>.</li>
2853<li>Small tweaks to splat compilation, backticks, slicing, and the error for duplicate keys in object literals.</li>
2854</ul>
2855<div class="anchor" id="1.3.3"></div>
2856<h2 class="header">
2857  <a href="https://github.com/jashkenas/coffeescript/compare/1.3.1...1.3.3">1.3.3</a>
2858  <span class="timestamp"> &mdash; <time datetime="2012-05-15">May 15, 2012</time></span>
2859</h2><ul>
2860<li>Due to the new semantics of JavaScript’s strict mode, CoffeeScript no longer guarantees that constructor functions have names in all runtimes. See <a href="https://github.com/jashkenas/coffeescript/issues/2052">#2052</a> for discussion.</li>
2861<li>Inside of a nested function inside of an instance method, it’s now possible to call <code>super</code> more reliably (walks recursively up).</li>
2862<li>Named loop variables no longer have different scoping heuristics than other local variables. (Reverts #643)</li>
2863<li>Fix for splats nested within the LHS of destructuring assignment.</li>
2864<li>Corrections to our compile time strict mode forbidding of octal literals.</li>
2865</ul>
2866<div class="anchor" id="1.3.1"></div>
2867<h2 class="header">
2868  <a href="https://github.com/jashkenas/coffeescript/compare/1.2.0...1.3.1">1.3.1</a>
2869  <span class="timestamp"> &mdash; <time datetime="2012-04-10">April 10, 2012</time></span>
2870</h2><ul>
2871<li>CoffeeScript now enforces all of JavaScript’s <strong>Strict Mode</strong> early syntax errors at compile time. This includes old-style octal literals, duplicate property names in object literals, duplicate parameters in a function definition, deleting naked variables, setting the value of <code>eval</code> or <code>arguments</code>, and more. See a full discussion at <a href="https://github.com/jashkenas/coffeescript/issues/1547">#1547</a>.</li>
2872<li>The REPL now has a handy new multi-line mode for entering large blocks of code. It’s useful when copy-and-pasting examples into the REPL. Enter multi-line mode with <code>Ctrl-V</code>. You may also now pipe input directly into the REPL.</li>
2873<li>CoffeeScript now prints a <code>Generated by CoffeeScript VERSION</code> header at the top of each compiled file.</li>
2874<li>Conditional assignment of previously undefined variables <code>a or= b</code> is now considered a syntax error.</li>
2875<li>A tweak to the semantics of <code>do</code>, which can now be used to more easily simulate a namespace: <code>do (x = 1, y = 2) -&gt; …</code></li>
2876<li>Loop indices are now mutable within a loop iteration, and immutable between them.</li>
2877<li>Both endpoints of a slice are now allowed to be omitted for consistency, effectively creating a shallow copy of the list.</li>
2878<li>Additional tweaks and improvements to <code>coffee --watch</code> under Node’s “new” file watching API. Watch will now beep by default if you introduce a syntax error into a watched script. We also now ignore hidden directories by default when watching recursively.</li>
2879</ul>
2880<div class="anchor" id="1.2.0"></div>
2881<h2 class="header">
2882  <a href="https://github.com/jashkenas/coffeescript/compare/1.1.3...1.2.0">1.2.0</a>
2883  <span class="timestamp"> &mdash; <time datetime="2011-12-18">December 18, 2011</time></span>
2884</h2><ul>
2885<li>Multiple improvements to <code>coffee --watch</code> and <code>--join</code>. You may now use both together, as well as add and remove files and directories within a <code>--watch</code>’d folder.</li>
2886<li>The <code>throw</code> statement can now be used as part of an expression.</li>
2887<li>Block comments at the top of the file will now appear outside of the safety closure wrapper.</li>
2888<li>Fixed a number of minor 1.1.3 regressions having to do with trailing operators and unfinished lines, and a more major 1.1.3 regression that caused boun
2888d functions <em>within</em> bound class functions to have the incorrect <code>this</code>.</li>
2889</ul>
2890<div class="anchor" id="1.1.3"></div>
2891<h2 class="header">
2892  <a href="https://github.com/jashkenas/coffeescript/compare/1.1.2...1.1.3">1.1.3</a>
2893  <span class="timestamp"> &mdash; <time datetime="2011-11-08">November 8, 2011</time></span>
2894</h2><ul>
2895<li>Ahh, whitespace. CoffeeScript’s compiled JS now tries to space things out and keep it readable, as you can see in the examples on this page.</li>
2896<li>You can now call <code>super</code> in class level methods in class bodies, and bound class methods now preserve their correct context.</li>
2897<li>JavaScript has always supported octal numbers <code>010 is 8</code>, and hexadecimal numbers <code>0xf is 15</code>, but CoffeeScript now also supports binary numbers: <code>0b10 is 2</code>.</li>
2898<li>The CoffeeScript module has been nested under a subdirectory to make it easier to <code>require</code> individual components separately, without having to use <strong>npm</strong>. For example, after adding the CoffeeScript folder to your path: <code>require('coffee-script/lexer')</code></li>
2899<li>There’s a new “link” feature in Try CoffeeScript on this webpage. Use it to get a shareable permalink for your example script.</li>
2900<li>The <code>coffee --watch</code> feature now only works on Node.js 0.6.0 and higher, but now also works properly on Windows.</li>
2901<li>Lots of small bug fixes from <strong><a href="https://github.com/michaelficarra">@michaelficarra</a></strong>, <strong><a href="https://github.com/geraldalewis">@geraldalewis</a></strong>, <strong><a href="https://github.com/satyr">@satyr</a></strong>, and <strong><a href="https://github.com/trevorburnham">@trevorburnham</a></strong>.</li>
2902</ul>
2903<div class="anchor" id="1.1.2"></div>
2904<h2 class="header">
2905  <a href="https://github.com/jashkenas/coffeescript/compare/1.1.1...1.1.2">1.1.2</a>
2906  <span class="timestamp"> &mdash; <time datetime="2011-08-04">August 4, 2011</time></span>
2907</h2><p>Fixes for block comment formatting, <code>?=</code> compilation, implicit calls against control structures, implicit invocation of a try/catch block, variadic arguments leaking from local scope, line numbers in syntax errors following heregexes, property access on parenthesized number literals, bound class methods and super with reserved names, a REPL overhaul, consecutive compiled semicolons, block comments in implicitly called objects, and a Chrome bug.</p>
2908<div class="anchor" id="1.1.1"></div>
2909<h2 class="header">
2910  <a href="https://github.com/jashkenas/coffeescript/compare/1.1.0...1.1.1">1.1.1</a>
2911  <span class="timestamp"> &mdash; <time datetime="2011-05-10">May 10, 2011</time></span>
2912</h2><p>Bugfix release for classes with external constructor functions, see issue #1182.</p>
2913<div class="anchor" id="1.1.0"></div>
2914<h2 class="header">
2915  <a href="https://github.com/jashkenas/coffeescript/compare/1.0.1...1.1.0">1.1.0</a>
2916  <span class="timestamp"> &mdash; <time datetime="2011-05-01">May 1, 2011</time></span>
2917</h2><p>When running via the <code>coffee</code> executable, <code>process.argv</code> and friends now report <code>coffee</code> instead of <code>node</code>. Better compatibility with <strong>Node.js 0.4.x</strong> module lookup changes. The output in the REPL is now colorized, like Node’s is. Giving your concatenated CoffeeScripts a name when using <code>--join</code> is now mandatory. Fix for lexing compound division <code>/=</code> as a regex accidentally. All <code>text/coffeescript</code> tags should now execute in the order they’re included. Fixed an issue with extended subclasses using external constructor functions. Fixed an edge-case infinite loop in <code>addImplicitParentheses</code>. Fixed exponential slowdown with long chains of function calls. Globals no longer leak into the CoffeeScript REPL. Splatted parameters are declared local to the function.</p>
2918<div class="anchor" id="1.0.1"></div>
2919<h2 class="header">
2920  <a href="https://github.com/jashkenas/coffeescript/compare/1.0.0...1.0.1">1.0.1</a>
2921  <span class="timestamp"> &mdash; <time datetime="2011-01-31">January 31, 2011</time></span>
2922</h2><p>Fixed a lexer bug with Unicode identifiers. Updated REPL for compatibility with Node.js 0.3.7. Fixed requiring relative paths in the REPL. Trailing <code>return</code> and <code>return undefined</code> are now optimized away. Stopped requiring the core Node.js <code>util</code> module for back-compatibility with Node.js 0.2.5. Fixed a case where a conditional <code>return</code> would cause fallthrough in a <code>switch</code> statement. Optimized empty objects in destructuring assignment.</p>
2923<div class="anchor" id="1.0.0"></div>
2924<h2 class="header">
2925  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.6...1.0.0">1.0.0</a>
2926  <span class="timestamp"> &mdash; <time datetime="2010-12-24">December 24, 2010</time></span>
2927</h2><p>CoffeeScript loops no longer try to preserve block scope when functions are being generated 
2927within the loop body. Instead, you can use the <code>do</code> keyword to create a convenient closure wrapper. Added a <code>--nodejs</code> flag for passing through options directly to the <code>node</code> executable. Better behavior around the use of pure statements within expressions. Fixed inclusive slicing through <code>-1</code>, for all browsers, and splicing with arbitrary expressions as endpoints.</p>
2928<div class="anchor" id="0.9.6"></div>
2929<h2 class="header">
2930  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.5...0.9.6">0.9.6</a>
2931  <span class="timestamp"> &mdash; <time datetime="2010-12-06">December 6, 2010</time></span>
2932</h2><p>The REPL now properly formats stacktraces, and stays alive through asynchronous exceptions. Using <code>--watch</code> now prints timestamps as files are compiled. Fixed some accidentally-leaking variables within plucked closure-loops. Constructors now maintain their declaration location within a class body. Dynamic object keys were removed. Nested classes are now supported. Fixes execution context for naked splatted functions. Bugfix for inversion of chained comparisons. Chained class instantiation now works properly with splats.</p>
2933<div class="anchor" id="0.9.5"></div>
2934<h2 class="header">
2935  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.4...0.9.5">0.9.5</a>
2936  <span class="timestamp"> &mdash; <time datetime="2010-11-21">November 21, 2010</time></span>
2937</h2><p>0.9.5 should be considered the first release candidate for CoffeeScript 1.0. There have been a large number of internal changes since the previous release, many contributed from <strong>satyr</strong>’s <a href="https://github.com/satyr/coco">Coco</a> dialect of CoffeeScript. Heregexes (extended regexes) were added. Functions can now have default arguments. Class bodies are now executable code. Improved syntax errors for invalid CoffeeScript. <code>undefined</code> now works like <code>null</code>, and cannot be assigned a new value. There was a precedence change with respect to single-line comprehensions: <code>result = i for i in list</code>
2938used to parse as <code>result = (i for i in list)</code> by default … it now parses as
2939<code>(result = i) for i in list</code>.</p>
2940<div class="anchor" id="0.9.4"></div>
2941<h2 class="header">
2942  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.3...0.9.4">0.9.4</a>
2943  <span class="timestamp"> &mdash; <time datetime="2010-09-21">September 21, 2010</time></span>
2944</h2><p>CoffeeScript now uses appropriately-named temporary variables, and recycles their references after use. Added <code>require.extensions</code> support for <strong>Node.js 0.3</strong>. Loading CoffeeScript in the browser now adds just a single <code>CoffeeScript</code> object to global scope. Fixes for implicit object and block comment edge cases.</p>
2945<div class="anchor" id="0.9.3"></div>
2946<h2 class="header">
2947  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.2...0.9.3">0.9.3</a>
2948  <span class="timestamp"> &mdash; <time datetime="2010-09-16">September 16, 2010</time></span>
2949</h2><p>CoffeeScript <code>switch</code> statements now compile into JS <code>switch</code> statements — they previously compiled into <code>if/else</code> chains for JavaScript 1.3 compatibility. Soaking a function invocation is now supported. Users of the RubyMine editor should now be able to use <code>--watch</code> mode.</p>
2950<div class="anchor" id="0.9.2"></div>
2951<h2 class="header">
2952  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.1...0.9.2">0.9.2</a>
2953  <span class="timestamp"> &mdash; <time datetime="2010-08-23">August 23, 2010</time></span>
2954</h2><p>Specifying the start and end of a range literal is now optional, eg. <code>array[3..]</code>. You can now say <code>a not instanceof b</code>. Fixed important bugs with nested significant and non-significant indentation (Issue #637). Added a <code>--require</code> flag that allows you to hook into the <code>coffee</code> command. Added a custom <code>jsl.conf</code> file for our preferred JavaScriptLint setup. Sped up Jison grammar compilation time by flattening rules for operations. Block comments can now be used with JavaScript-minifier-friendly syntax. Added JavaScript’s compound assignment bitwise operators. Bugfixes to implicit object literals with leading number and string keys, as the subject of implicit calls, and as part of compound assignment.</p>
2955<div class="anchor" id="0.9.1"></div>
2956<h2 class="header">
2957  <a href="https://github.com/jashkenas/coffeescript/compare/0.9.0...0.9.1">0.9.1</a>
2958  <span class="timestamp"> &mdash; <time datetime="2010-08-11">August 11, 2010</time></span>
2959</h2><p>Bugfix release for <strong>0.9.1</strong>. Greatly improves the handling of mixed implicit objects, implicit function calls, and implicit indentation. String and regex interpolation is now strictly <code>#{ … }</code> (Ruby style). The compiler now takes a <code>--require</code> flag, which specifies scripts to run before compilation.</p>
2960<div class="anchor" id="0.9.0"></div>
2961<h2 class="header">
2962  <a href="https://github.com/jashkenas/coffeescript/compare/0.7.2...0.9.0">0.9.0</a>
2963  <span class="timestamp"> &mdash; <time datetime="2010-08-04">August 4, 2010</time></span>
2964</h2><p>The CoffeeScript <strong>0.9</strong> series is considered to be a release candidate for <strong>1.0</strong>; let’s give her a shakedown cruise. <strong>0.9.0</strong> introduces a massive backwards-incompatible change: Assignment now uses <code>=</code>, and object literals use <code>:</code>, as in JavaScript. This allows us to have implicit object literals, and YAML-style object definitions. Half assignments are removed, in favor of <code>+=</code>, <code>or=</code>, and friends. Interpolation now uses a hash mark <code>#</code> instead of the dollar sign <code>$</code> — because dollar signs may be part of a valid JS identifier. Downwards range comprehensions are now safe again, and are optimized to straight for loops when created with integer endpoints. A fast, unguarded form of object c
2964omprehension was added: <code>for all key, value of object</code>. Mentioning the <code>super</code> keyword with no arguments now forwards all arguments passed to the function, as in Ruby. If you extend class <code>B</code> from parent class <code>A</code>, if <code>A</code> has an <code>extended</code> method defined, it will be called, passing in <code>B</code> — this enables static inheritance, among other things. Cleaner output for functions bound with the fat arrow. <code>@variables</code> can now be used in parameter lists, with the parameter being automatically set as a property on the object — useful in constructors and setter functions. Constructor functions can now take splats.</p>
2965<div class="anchor" id="0.7.2"></div>
2966<h2 class="header">
2967  <a href="https://github.com/jashkenas/coffeescript/compare/0.7.1...0.7.2">0.7.2</a>
2968  <span class="timestamp"> &mdash; <time datetime="2010-07-12">July 12, 2010</time></span>
2969</h2><p>Quick bugfix (right after 0.7.1) for a problem that prevented <code>coffee</code> command-line options from being parsed in some circumstances.</p>
2970<div class="anchor" id="0.7.1"></div>
2971<h2 class="header">
2972  <a href="https://github.com/jashkenas/coffeescript/compare/0.7.0...0.7.1">0.7.1</a>
2973  <span class="timestamp"> &mdash; <time datetime="2010-07-11">July 11, 2010</time></span>
2974</h2><p>Block-style comments are now passed through and printed as JavaScript block comments – making them useful for licenses and copyright headers. Better support for running coffee scripts standalone via hashbangs. Improved syntax errors for tokens that are not in the grammar.</p>
2975<div class="anchor" id="0.7.0"></div>
2976<h2 class="header">
2977  <a href="https://github.com/jashkenas/coffeescript/compare/0.6.2...0.7.0">0.7.0</a>
2978  <span class="timestamp"> &mdash; <time datetime="2010-06-28">June 28, 2010</time></span>
2979</h2><p>Official CoffeeScript variable style is now camelCase, as in JavaScript. Reserved words are now allowed as object keys, and will be quoted for you. Range comprehensions now generate cleaner code, but you have to specify <code>by -1</code> if you’d like to iterate downward. Reporting of syntax errors is greatly improved from the previous release. Running <code>coffee</code> with no arguments now launches the REPL, with Readline support. The <code>&lt;-</code> bind operator has been removed from CoffeeScript. The <code>loop</code> keyword was added, which is equivalent to a <code>while true</code> loop. Comprehensions that contain closures will now close over their variables, like the semantics of a <code>forEach</code>. You can now use bound function in class definitions (bound to the instance). For consistency, <code>a in b</code> is now an array presence check, and <code>a of b</code> is an object-key check. Comments are no longer passed through to the generated JavaScript.</p>
2980<div class="anchor" id="0.6.2"></div>
2981<h2 class="header">
2982  <a href="https://github.com/jashkenas/coffeescript/compare/0.6.1...0.6.2">0.6.2</a>
2983  <span class="timestamp"> &mdash; <time datetime="2010-05-15">May 15, 2010</time></span>
2984</h2><p>The <code>coffee</code> command will now preserve directory structure when compiling a directory full of scripts. Fixed two omissions that were preventing the CoffeeScript compiler from running live within Internet Explorer. There’s now a syntax for block comments, similar in spirit to CoffeeScript’s heredocs. ECMA Harmony DRY-style pattern matching is now supported, where the name of the property is the same as the name of the value: <code>{name, length}: func</code>. Pattern matching is now allowed within comprehension variables. <code>unless</code> is now allowed in block form. <code>until</code> loops were added, as the inverse of <code>while</code> loops. <code>switch</code> statements are now allowed without switch object clauses. Compatible with Node.js <strong>v0.1.95</strong>.</p>
2985<div class="anchor" id="0.6.1"></div>
2986<h2 class="header">
2987  <a href="https://github.com/jashkenas/coffeescript/compare/0.6.0...0.6.1">0.6.1</a>
2988  <span class="timestamp"> &mdash; <time datetime="2010-04-12">April 12, 2010</time></span>
2989</h2><p>Upgraded CoffeeScript for compatibility with the new Node.js <strong>v0.1.90</strong> series.</p>
2990<div class="anchor" id="0.6.0"></div>
2991<h2 class="header">
2992  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.6...0.6.0">
29920.6.0</a>
2993  <span class="timestamp"> &mdash; <time datetime="2010-04-03">April 3, 2010</time></span>
2994</h2><p>Trailing commas are now allowed, a-la Python. Static properties may be assigned directly within class definitions, using <code>@property</code> notation.</p>
2995<div class="anchor" id="0.5.6"></div>
2996<h2 class="header">
2997  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.5...0.5.6">0.5.6</a>
2998  <span class="timestamp"> &mdash; <time datetime="2010-03-23">March 23, 2010</time></span>
2999</h2><p>Interpolation can now be used within regular expressions and heredocs, as well as strings. Added the <code>&lt;-</code> bind operator. Allowing assignment to half-expressions instead of special <code>||=</code>-style operators. The arguments object is no longer automatically converted into an array. After requiring <code>coffee-script</code>, Node.js can now directly load <code>.coffee</code> files, thanks to <strong>registerExtension</strong>. Multiple splats can now be used in function calls, arrays, and pattern matching.</p>
3000<div class="anchor" id="0.5.5"></div>
3001<h2 class="header">
3002  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.4...0.5.5">0.5.5</a>
3003  <span class="timestamp"> &mdash; <time datetime="2010-03-08">March 8, 2010</time></span>
3004</h2><p>String interpolation, contributed by <a href="https://github.com/StanAngeloff">Stan Angeloff</a>. Since <code>--run</code> has been the default since <strong>0.5.3</strong>, updating <code>--stdio</code> and <code>--eval</code> to run by default, pass <code>--compile</code> as well if you’d like to print the result.</p>
3005<div class="anchor" id="0.5.4"></div>
3006<h2 class="header">
3007  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.3...0.5.4">0.5.4</a>
3008  <span class="timestamp"> &mdash; <time datetime="2010-03-03">March 3, 2010</time></span>
3009</h2><p>Bugfix that corrects the Node.js global constants <code>__filename</code> and <code>__dirname</code>. Tweaks for more flexible parsing of nested function literals and improperly-indented comments. Updates for the latest Node.js API.</p>
3010<div class="anchor" id="0.5.3"></div>
3011<h2 class="header">
3012  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.2...0.5.3">0.5.3</a>
3013  <span class="timestamp"> &mdash; <time datetime="2010-02-27">February 27, 2010</time></span>
3014</h2><p>CoffeeScript now has a syntax for defining classes. Many of the core components (Nodes, Lexer, Rewriter, Scope, Optparse) are using them. Cakefiles can use <code>optparse.coffee</code> to define options for tasks. <code>--run</code> is now the default flag for the <code>coffee</code> command, use <code>--compile</code> to save JavaScripts. Bugfix for an ambiguity between RegExp literals and chained divisions.</p>
3015<div class="anchor" id="0.5.2"></div>
3016<h2 class="header">
3017  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.1...0.5.2">0.5.2</a>
3018  <span class="timestamp"> &mdash; <time datetime="2010-02-25">February 25, 2010</time></span>
3019</h2><p>Added a compressed version of the compiler for inclusion in web pages as
3020<code>browser-compiler/coffee-script.js</code>. It’ll automatically run any script tags with type <code>text/coffeescript</code> for you. Added a <code>--stdio</code> option to the <code>coffee</code> command, for piped-in compiles.</p>
3021<div class="anchor" id="0.5.1"></div>
3022<h2 class="header">
3023  <a href="https://github.com/jashkenas/coffeescript/compare/0.5.0...0.5.1">0.5.1</a>
3024  <span class="timestamp"> &mdash; <time datetime="2010-02-24">February 24, 2010</time></span>
3025</h2><p>Improvements to null soaking with the existential operator, including soaks on indexed properties. Added conditions to <code>while</code> loops, so you can use them as filters with <code>when</code>, in the same manner as comprehensions.</p>
3026<div class="anchor" id="0.5.0"></div>
3027<h2 class="header">
3028  <a href="https://github.com/jashkenas/coffeescript/compare/0.3.2...0.5.0">0.5.0</a>
3029  <span class="timestamp"> &mdash; <time datetime="2010-02-21">February 21, 2010</time></span>
3030</h2><p>CoffeeScript 0.5.0 is a major release, While there are no language changes, the Ruby compiler has been removed in favor of a self-hosting compiler written in pure CoffeeScript.</p>
3031<div class="anchor" id="0.3.2"></div>
3032<h2 class="header">
3033  <a href="https://github.com/jashkenas/coffeescript/compare/0.3.0...0.3.2">0.3.2</a>
3034  <span class="timestamp"> &mdash; <time datetime="2010-02-08">February 8, 2010</time></span>
3035</h2><p><code>@property</code> is now a shorthand for <code>this.property</code>.
3036Switched the default JavaScript engine from Narwhal to Node.js. Pass the <code>--narwhal</code> flag if you’d like to continue using it.</p>
3037<div class="anchor" id="0.3.0"></div>
3038<h2 class="header">
3039  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.6...0.3.0">0.3.0</a>
3040  <span class="timestamp"> &mdash; <time datetime="2010-01-26">January 26, 2010</time></span>
3041</h2><p>CoffeeScript 0.3 includes major syntax changes:
3042The function symbol was changed to <code>-&gt;</code>, and the bound function symbol is now <code>=&gt;</code>.
3043Parameter lists in function definitions must now be wrapped in parentheses.
3044Added property soaking, with the <code>?.</code> operator.
3045Made parentheses optional, when invoking functions with arguments.
3046Removed the obsolete block literal syntax.</p>
3047<div class="anchor" id="0.2.6"></div>
3048<h2 class="header">
3049  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.5...0.2.6">0.2.6</a>
3050  <span class="timestamp"> &mdash; <time datetime="2010-01-17">January 17, 2010</time></span>
3051</h2><p>Added Python-style chained comparisons, the conditional existence operator <code>?=</code>, and some examples from <em>Beautiful Code</em>. Bugfixes relating to statement-to-expression conversion, arguments-to-array conversion, and the TextMate syntax highlighter.</p>
3052<div class="anchor" id="0.2.5"></div>
3053<h2 class="header">
3054  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.4...0.2.5">0.2.5</a>
3055  <span class="timestamp"> &mdash; <time datetime="2010-01-13">January 13, 2010</time></span>
3056</h2><p>The conditions in switch statements can now take multiple values at once — If any of them are true, the case will run. Added the long arrow <code>==&gt;</code>, which defines and immediately binds a function to <code>this</code>. While loops can now be used as expressions, in the same way that comprehensions can. Splats can be used within pattern matches to soak up the rest of an array.</p>
3057<div class="anchor" id="0.2.4"></div>
3058<h2 class="header">
3059  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.3...0.2.4">
30590.2.4</a>
3060  <span class="timestamp"> &mdash; <time datetime="2010-01-12">January 12, 2010</time></span>
3061</h2><p>Added ECMAScript Harmony style destructuring assignment, for dealing with extracting values from nested arrays and objects. Added indentation-sensitive heredocs for nicely formatted strings or chunks of code.</p>
3062<div class="anchor" id="0.2.3"></div>
3063<h2 class="header">
3064  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.2...0.2.3">0.2.3</a>
3065  <span class="timestamp"> &mdash; <time datetime="2010-01-11">January 11, 2010</time></span>
3066</h2><p>Axed the unsatisfactory <code>ino</code> keyword, replacing it with <code>of</code> for object comprehensions. They now look like: <code>for prop, value of object</code>.</p>
3067<div class="anchor" id="0.2.2"></div>
3068<h2 class="header">
3069  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.1...0.2.2">0.2.2</a>
3070  <span class="timestamp"> &mdash; <time datetime="2010-01-10">January 10, 2010</time></span>
3071</h2><p>When performing a comprehension over an object, use <code>ino</code>, instead of <code>in</code>, which helps us generate smaller, more efficient code at compile time.
3072Added <code>::</code> as a shorthand for saying <code>.prototype.</code>
3073The “splat” symbol has been changed from a prefix asterisk <code>*</code>, to a postfix ellipsis <code>...</code>
3074Added JavaScript’s <code>in</code> operator, empty <code>return</code> statements, and empty <code>while</code> loops.
3075Constructor functions that start with capital letters now include a safety check to make sure that the new instance of the object is returned.
3076The <code>extends</code> keyword now functions identically to <code>goog.inherits</code> in Google’s Closure Library.</p>
3077<div class="anchor" id="0.2.1"></div>
3078<h2 class="header">
3079  <a href="https://github.com/jashkenas/coffeescript/compare/0.2.0...0.2.1">0.2.1</a>
3080  <span class="timestamp"> &mdash; <time datetime="2010-01-05">January 5, 2010</time></span>
3081</h2><p>Arguments objects are now converted into real arrays when referenced.</p>
3082<div class="anchor" id="0.2.0"></div>
3083<h2 class="header">
3084  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.6...0.2.0">0.2.0</a>
3085  <span class="timestamp"> &mdash; <time datetime="2010-01-05">January 5, 2010</time></span>
3086</h2><p>Major release. Significant whitespace. Better statement-to-expression conversion. Splats. Splice literals. Object comprehensions. Blocks. The existential operator. Many thanks to all the folks who posted issues, with special thanks to <a href="https://github.com/liamoc">Liam O’Connor-Davis</a> for whitespace and expression help.</p>
3087<div class="anchor" id="0.1.6"></div>
3088<h2 class="header">
3089  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.5...0.1.6">0.1.6</a>
3090  <span class="timestamp"> &mdash; <time datetime="2009-12-27">December 27, 2009</time></span>
3091</h2><p>Bugfix for running <code>coffee --interactive</code> and <code>--run</code> from outside of the CoffeeScript directory. Bugfix for nested function/if-statements.</p>
3092<div class="anchor" id="0.1.5"></div>
3093<h2 class="header">
3094  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.4...0.1.5">0.1.5</a>
3095  <span class="timestamp"> &mdash; <time datetime="2009-12-26">December 26, 2009</time></span>
3096</h2><p>Array slice literals and array comprehensions can now both take Ruby-style ranges to specify the start and end. JavaScript variable declaration is now pushed up to the top of the scope, making all assignment statements into expressions. You can use <code>\</code> to escape newlines. The <code>coffee-script</code> command is now called <code>coffee</code>.</p>
3097<div class="anchor" id="0.1.4"></div>
3098<h2 class="header">
3099  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.3...0.1.4">0.1.4</a>
3100  <span class="timestamp"> &mdash; <time datetime="2009-12-25">December 25, 2009</time></span>
3101</h2><p>The official CoffeeScript extension is now <code>.coffee</code> instead of <code>.cs</code>, which properly belongs to <a href="https://en.wikipedia.org/wiki/C_Sharp_(programming_language)">C#</a>. Due to popular demand, you can now also use <code>=</code> to assign. Unlike JavaScript, <code>=</code> can also be used within object literals, interchangeably with <code>:</code>. Made a grammatical fix for chained function calls like <code>func(1)(2)(3)(4)</code>. Inheritance and super no longer use <code>__proto__</code>, so they should be IE-compatible now.</p>
3102<div class="anchor" id="0.1.3"></div>
3103<h2 class="header">
3104  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.2...0.1.3">0.1.3</a>
3105  <span class="timestamp"> &mdash; <time datetime="2009-12-25">December 25, 2009</time></span>
3106</h2><p>The <code>coffee</code> command now includes <code>--interactive</code>
3106, which launches an interactive CoffeeScript session, and <code>--run</code>, which directly compiles and executes a script. Both options depend on a working installation of Narwhal. The <code>aint</code> keyword has been replaced by <code>isnt</code>, which goes together a little smoother with <code>is</code>. Quoted strings are now allowed as identifiers within object literals: eg. <code>{&quot;5+5&quot;: 10}</code>. All assignment operators now use a colon: <code>+:</code>, <code>-:</code>, <code>*:</code>, etc.</p>
3107<div class="anchor" id="0.1.2"></div>
3108<h2 class="header">
3109  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.1...0.1.2">0.1.2</a>
3110  <span class="timestamp"> &mdash; <time datetime="2009-12-24">December 24, 2009</time></span>
3111</h2><p>Fixed a bug with calling <code>super()</code> through more than one level of inheritance, with the re-addition of the <code>extends</code> keyword. Added experimental <a href="http://narwhaljs.org/">Narwhal</a> support (as a Tusk package), contributed by <a href="http://blog.tlrobinson.net/">Tom Robinson</a>, including <strong>bin/cs</strong> as a CoffeeScript REPL and interpreter. New <code>--no-wrap</code> option to suppress the safety function wrapper.</p>
3112<div class="anchor" id="0.1.1"></div>
3113<h2 class="header">
3114  <a href="https://github.com/jashkenas/coffeescript/compare/0.1.0...0.1.1">0.1.1</a>
3115  <span class="timestamp"> &mdash; <time datetime="2009-12-24">December 24, 2009</time></span>
3116</h2><p>Added <code>instanceof</code> and <code>typeof</code> as operators.</p>
3117<div class="anchor" id="0.1.0"></div>
3118<h2 class="header">
3119  <a href="https://github.com/jashkenas/coffeescript/compare/8e9d637985d2dc9b44922076ad54ffef7fa8e9c2...0.1.0">0.1.0</a>
3120  <span class="timestamp"> &mdash; <time datetime="2009-12-24">December 24, 2009</time></span>
3121</h2><p>Initial CoffeeScript release.</p>
3122
3123</div>
3124
3125
3126<script type="text/coffeescript">
3127sourceFragment = "try:"
3128
3129# Set up the compilation function, to run when you stop typing.
3130compileSource = ->
3131  source = $('#repl_source').val()
3132  results = $('#repl_results')
3133  window.compiledJS = ''
3134  try
3135    window.compiledJS = CoffeeScript.compile source, bare: on
3136    el = results[0]
3137    if el.innerText
3138      el.innerText = window.compiledJS
3139    else
3140      results.text(window.compiledJS)
3141    results.removeClass 'error'
3142    $('.minibutton.run').removeClass 'error'
3143  catch {location, message}
3144    if location?
3145      message = "Error on line #{location.first_line + 1}: #{message}"
3146    results.text(message).addClass 'error'
3147    $('.minibutton.run').addClass 'error'
3148
3149  # Update permalink
3150  $('#repl_permalink').attr 'href', "##{sourceFragment}#{encodeURIComponent source}"
3151
3152# Listen for keypresses and recompile.
3153$('#repl_source').keyup -> compileSource()
3154
3155# Use tab key to insert tabs
3156$('#repl_source').keydown (e) ->
3157  if e.keyCode is 9
3158    e.preventDefault()
3159    textbox = e.target
3160    # Insert tab character at caret or in selection
3161    textbox.value = textbox.value[0...textbox.selectionStart] + "\t" + textbox.value[textbox.selectionEnd...]
3162    # Put caret in correct position
3163    textbox.selectionEnd = ++textbox.selectionStart
3164
3165# Eval the compiled js.
3166evalJS = ->
3167  try
3168    eval window.compiledJS
3169  catch error then alert error
3170
3171# Load the console with a string of CoffeeScript.
3172window.loadConsole = (coffee) ->
3173  $('#repl_source').val coffee
3174  compileSource()
3175  $('.navigation.try').addClass('active')
3176  false
3177
3178# Helper to hide the menus.
3179closeMenus = ->
3180  $('.navigation.active').removeClass 'active'
3181
3182$('.minibutton.run').click -> evalJS()
3183
3184# Bind navigation buttons to open the menus.
3185$('.navigation').click (e) ->
3186  return if e.target.tagName.toLowerCase() is 'a'
3187  return false if $(e.target).closest('.repl_wrapper').length
3188  if $(this).hasClass('active')
3189    closeMenus()
3190  else
3191    closeMenus()
3192    $(this).addClass 'active'
3193  false
3194
3195$(document).on 'click', '[href="#try"]', (e) ->
3196  $('.navigation.try').addClass 'active'
3197
3198# Dismiss console if Escape pressed or click falls outside console
3199# Trigger Run button on Ctrl-Enter
3200$(document.body)
3201  .keydown (e) ->
3202    closeMenus() if e.which == 27
3203    evalJS() if e.which == 13 and (e.metaKey or e.ctrlKey) and $('.minibutton.run:visible').length
3204  .click (e) ->
3205    return false if $(e.target).hasClass('minibutton')
3206    closeMenus()
3207
3208$('#open_webchat').click ->
3209  $(this).replaceWith $('<iframe src="http://webchat.freenode.net/?channels=coffeescript" width="625" height="400"></iframe>')
3210
3211$("#repl_permalink").click (e) ->
3212    window.location = $(this).attr("href")
3213    false
3214
3215# If source code is included in location.hash, display it.
3216hash = decodeURIComponent location.hash.replace(/^#/, '')
3217if hash.indexOf(sourceFragment) == 0
3218    src = hash.substr sourceFragment.length
3219    loadConsole src
3220
3221compileSource()
3222
3223</script>
3223
3224
3225<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
vendor: 1 bytes, line 3225
3225
3226<script src="browser-compiler/coffee-script.js"></script>
3226
3227
3228<script type="module" src="https://static.cloudflareinsights.com/beacon.min.js/v31edd6df95cf4e85bb4c19e7a9bdbcba1788362987495" integrity="sha512-iIg7k2xntmwu6/uSb5tpc/hySgZc4eoL31yB29W6tJFo2akwjPWcEqnCEdJvGexCL0KEQwVYv5BlowfhVz26hg==" data-cf-beacon='{"version":"2024.11.0","token":"3bf2bd78e087451ea36567e241d6aa66","r":1,"spa":2}' crossorigin="anonymous"></script>
3228
3229</body>
3230</html>

Line numbers count LF bytes from the start of the resource, as the search results do. Vendor segments are library code the classifier recognised; they are stored but not indexed. Bytes are shown as Latin1 characters, one per byte.