https://www.diariodelacarne.cl/js/echo-master/dist/echo.js

1/*! echo-js v1.7.3 | (c) 2016 @toddmotto | https://github.com/toddmotto/echo */
2(function (root, factory) {
3  if (typeof define === 'function' && define.amd) {
4    define(function() {
5      return factory(root);
6    });
7  } else if (typeof exports === 'object') {
8    module.exports = factory;
9  } else {
10    root.echo = factory(root);
11  }
12})(this, function (root) {
13
14  'use strict';
15
16  var echo = {};
17
18  var callback = function () {};
19
20  var offset, poll, delay, useDebounce, unload;
21
22  var isHidden = function (element) {
23    return (element.offsetParent === null);
24  };
25  
26  var inView = function (element, view) {
27    if (isHidden(element)) {
28      return false;
29    }
30
31    var box = element.getBoundingClientRect();
32    return (box.right >= view.l && box.bottom >= view.t && box.left <= view.r && box.top <= view.b);
33  };
34
35  var debounceOrThrottle = function () {
36    if(!useDebounce && !!poll) {
37      return;
38    }
39    clearTimeout(poll);
40    poll = setTimeout(function(){
41      echo.render();
42      poll = null;
43    }, delay);
44  };
45
46  echo.init = function (opts) {
47    opts = opts || {};
48    var offsetAll = opts.offset || 0;
49    var offsetVertical = opts.offsetVertical || offsetAll;
50    var offsetHorizontal = opts.offsetHorizontal || offsetAll;
51    var optionToInt = function (opt, fallback) {
52      return parseInt(opt || fallback, 10);
53    };
54    offset = {
55      t: optionToInt(opts.offsetTop, offsetVertical),
56      b: optionToInt(opts.offsetBottom, offsetVertical),
57      l: optionToInt(opts.offsetLeft, offsetHorizontal),
58      r: optionToInt(opts.offsetRight, offsetHorizontal)
59    };
60    delay = optionToInt(opts.throttle, 250);
61    useDebounce = opts.debounce !== false;
62    unload = !!opts.unload;
63    callback = opts.callback || callback;
64    echo.render();
65    if (document.addEventListener) {
66      root.addEventListener('scroll', debounceOrThrottle, false);
67      root.addEventListener('load', debounceOrThrottle, false);
68    } else {
69      root.attachEvent('onscroll', debounceOrThrottle);
70      root.attachEvent('onload', debounceOrThrottle);
71    }
72  };
73
74  echo.render = function (context) {
75    var nodes = (context || document).querySelectorAll('[data-echo], [data-echo-background]');
76    var length = nodes.length;
77    var src, elem;
78    var view = {
79      l: 0 - offset.l,
80      t: 0 - offset.t,
81      b: (root.innerHeight || document.documentElement.clientHeight) + offset.b,
82      r: (root.innerWidth || document.documentElement.clientWidth) + offset.r
83    };
84    for (var i = 0; i < length; i++) {
85      elem = nodes[i];
86      if (inView(elem, view)) {
87
88        if (unload) {
89          elem.setAttribute('data-echo-placeholder', elem.src);
90        }
91
92        if (elem.getAttribute('data-echo-background') !== null) {
93          elem.style.backgroundImage = 'url(' + elem.getAttribute('data-echo-background') + ')';
94        }
95        else if (elem.src !== (src = elem.getAttribute('data-echo'))) {
96          elem.src = src;
97        }
98
99        if (!unload) {
100          elem.removeAttribute('data-echo');
101          elem.removeAttribute('data-echo-background');
102        }
103
104        callback(elem, 'load');
105      }
106      else if (unload && !!(src = elem.getAttribute('data-echo-placeholder'))) {
107
108        if (elem.getAttribute('data-echo-background') !== null) {
109          elem.style.backgroundImage = 'url(' + src + ')';
110        }
111        else {
112          elem.src = src;
113        }
114
115        elem.removeAttribute('data-echo-placeholder');
116        callback(elem, 'unload');
117      }
118    }
119    if (!length) {
120      echo.detach();
121    }
122  };
123
124  echo.detach = function () {
125    if (document.removeEventListener) {
126      root.removeEventListener('scroll', debounceOrThrottle);
127    } else {
128      root.detachEvent('onscroll', debounceOrThrottle);
129    }
130    clearTimeout(poll);
131  };
132
133  return echo;
134
135});