https://mascva.ru/js/extsrc.js

1// http://whiteposts.com/extsrc
2// Released as BSD license
3// Author: Slava <[email protected]>
4
5/*
6
7extlib.js is a script that allow to defer loading SCRIPTs in HTML page until
8after the page renders. It supports deferred document.write too by creating
9SPAN tag after the SCRIPT and then document.write actually set's that tag's
10innerHTML.
11
12** HOW TO USE **
13
14<script src="extsrc.js"></script>
15
16<script extsrc="..."></script>   <-- this form is used when external script 
17                                     uses document.write
18
19<script asyncsrc="..."></script> <-- this form is used when external script 
20                                     doesn't use document.write
21
22Keep in mind that if your external script writes unbalanced tag, like so:
23document.write('<a href=#>'), it will be automatically closed (since extsrc
24creates a SPAN element after <script> element and assigns '<a href=#>' 
25to it as innerHTML to simluate document.write - the browser automatically
26will close the unbalanced A: '<a href="#"></a>').
27
28
29** extsrc.complete **
30
31You can also use extsrc.complete(). 
32Note that it runs only after ALL extsrc's are finished loading (NOT when 
33document is ready to render).
34
35extsrc.complete(function() { 
36    alert('All extsrcs loaded!'); 
37});
38
39
40Thanks to: Kolyaj, arestov, Zitrix, it2days, DriverX, maxpain, dhj, rednaxi,
41           Panya, sirus, MiXei4, hyborg and everyone else who helped test and 
42           develop.
43
44*/
45
46var extsrc = null;
47
48(function(){
49    extsrc = new Object;
50
51    extsrc.complete = function(f) {
52        this.complete.funcs.push(f);
53    };
54    extsrc.complete.funcs = [];
55
56
57

58    //document.write('<div id=console></div>');
59    //var console = document.getElementById('console');
60
61    var document_write = document.write;
62    var document_writeln = document.writeln;
63    var buffer = ''; // catching things like d.w('<scr');d.w('ipt></sc');...
64
65    var span = ''; // this is the new element that acts as a placeholder for 
66                   // future document.write's
67    
68    function dumpBuffer() {
69        if(buffer && span) {
70            document.write = document_write;
71            document.writeln = document_writeln;
72            var txt = document.createElement('span'); 
73            txt.innerHTML = buffer;
74            span.appendChild(txt);
75            buffer = '';
76        };
77    };
78    
79    function runNextScript() {
80        dumpBuffer();
81
82        var scripts = document.getElementsByTagName('script');
83        for(var i=0;i<scripts.length;i++) {
84            // go through all scripts, looking for those with extsrc or asyncsrc
85            // attributes. when encountered - set attribute to empty and return
86            // from runNextScript.
87            // runNextScript will be called when the encountered scripts runs 
88            // or fails (onload, onerror (404), readystatechange (good/404)).
89        
90            var current_script = scripts[i];
91
92            var cur_asyncsrc = current_script.getAttribute('asyncsrc');
93            if(cur_asyncsrc) {
94                // asyncsrc means script doesn't use document.write - 
95                // we can use it all in parallel
96                
97                current_script.setAttribute('asyncsrc', ''); // don't run 2nd time
98                var s = document.createElement('script'); 
99                s.async = true;
100                s.src = cur_asyncsrc;
101                document.getElementsByTagName('head')[0].appendChild(s);
102            };
103            
104            var cur_extsrc = current_script.getAttribute('extsrc');
105            if(cur_extsrc) {
106                // extsrc means script does use document.write - we can have
107                // only one definition of document.write, so load sequentially
108                
109                current_script.setAttribute('extsrc', ''); // don't run 2nd time
110                
111                //console.innerHTML += 'start '+extsrc+'<br>'; 
112
113                span = document.createElement('span');
114                current_script.parentNode.insertBefore(span, current_script);
115
116                document.write = function(txt) {
117                    buffer += txt;
118                };
119
120                document.writeln = function(txt) {
121                    buffer += txt;
122                    buffer += '\n';
123                };
124                
125                var s = document.createElement('script'); 
126                s.async = true;
127                s.src = cur_extsrc;
128                
129                if(isIE()) {
130                    // IE
131                    
132                    s.onreadystatechange = function() { 
133                        //console.innerHTML += 'readychange '+this.src+' '+this.readyState+'?<br>'; 
134
135                        if(this.readyState == 'loaded' || this.readyState == 'complete') {
136                            runNextScript(); 
137                        };
138                    };
139                } else {
140                    if((navigator.userAgent.indexOf("Firefox")!=-1) || ('onerror' in s)) {
141                        // Firefox
142                        
143                        s.onload = runNextScript;
144                        s.onerror = runNextScript;
145                    } else {
146                        // Opera
147                        
148                        s.onload = runNextScript;
149                        s.onreadystatechange = runNextScript;
150                    };
151                };
152                document.getElementsByTagName('head')[0].appendChild(s);
153                return;            
154            };
155        };
156        dumpBuffer();
157        document.write = document_write;
158        document.writeln = document_writeln;
159        
160        for(var i=0; i<extsrc.complete.funcs.length; i++) {
161            extsrc.complete.funcs[i]();
162        };
163    };
164    
165    function isIE() {
166      return /msie/i.test(navigator.userAgent) && !/opera/i.test(navigator.userAgent);
167    };
168    
169    // Below is the code by
170    // Dean Edwards/Matthias Miller/John Resig
171    // that just acts as window.onload, but in browser-specific way
172

173    function init() {
174        if (arguments.callee.done) return;
175        arguments.callee.done = true;
176        runNextScript();
177    };
178
179    /* Mozilla/Firefox/Opera 9 */
180    if (document.addEventListener) {
181        document.addEventListener("DOMContentLoaded", init, false);
182    }
183
184    /* Internet Explorer */
185    /*@cc_on @*/
186    /*@if (@_win32)
187    document.write("<script id=\"__ie_onload\" defer=\"defer\" src=\"javascript:void(0)\"><\/script>");
188    var script = document.getElementById("__ie_onload");
189    script.onreadystatechange = function() {
190        if (this.readyState == "complete") {
191	    init();
192        }
193    };
194    /*@end @*/
195
196    /* Safari */
197    if (/WebKit/i.test(navigator.userAgent)) { // условие для Safari
198        var _timer = setInterval(function() {
199	    if (/loaded|complete/.test(document.readyState)) {
200	        clearInterval(_timer);
201	        init();
202	    }
203        }, 10);
204    }
205
206    /* rest */
207    window.onload = init;
208
209})();
210
211