Jquery实现ready()的源码

 1 function bindReady(){     
 2     if ( readyBound ) return;     
 3     readyBound = true;     
 4     
 5     // Mozilla, Opera and webkit nightlies currently support this event     
 6     if ( document.addEventListener ) {     
 7         // Use the handy event callback     
 8         document.addEventListener( "DOMContentLoaded", function(){     
 9             document.removeEventListener( "DOMContentLoaded", arguments.callee, false );     
10             jQuery.ready();     
11         }, false );     
12     
13     // If IE event model is used     
14     } else if ( document.attachEvent ) {     
15         // ensure firing before onload,     
16         // maybe late but safe also for iframes     
17         document.attachEvent("onreadystatechange", function(){     
18             if ( document.readyState === "complete" ) {     
19                 document.detachEvent( "onreadystatechange", arguments.callee );     
20                 jQuery.ready();     
21             }     
22         });     
23     
24         // If IE and not an iframe     
25         // continually check to see if the document is ready     
26         if ( document.documentElement.doScroll && typeof window.frameElement === "undefined" ) 
27           (function(){     
28             if ( jQuery.isReady ) return;     
29     
30             try {     
31                 // If IE is used, use the trick by Diego Perini     
32                 // http://javascript.nwbox.com/IEContentLoaded/     
33                 document.documentElement.doScroll("left");     
34             } catch( error ) {     
35                 setTimeout( arguments.callee, 0 );     
36                 return;     
37             }     
38     
39             // and execute any waiting functions     
40             jQuery.ready();     
41         })();     
42     }     
43     
44     // A fallback to window.onload, that will always work     
45     jQuery.event.add( window, "load", jQuery.ready );     
46 }