window.onload加载完毕的问题及解决方案（下）_javascript技巧



接上篇，其它方法：
一、在IE中还可以在onreadystatechange事件里进行判断
http://www.thefutureoftheweb.com/blog/adddomloadevent
这里有Jesse Skinner写了一段的脚本函数来解决各种浏览器的onload问题，。
http://img.jb51.net/jslib/adddomloadevent.js
代码如下:
/*
* (c)2006 Jesse Skinner/Dean Edwards/Matthias Miller/John Resig
* Special thanks to Dan Webb's domready.js Prototype extension
* and Simon Willison's addLoadEvent
*
* For more info, see:
* http://www.thefutureoftheweb.com/blog/adddomloadevent
* http://dean.edwards.name/weblog/2006/06/again/
* http://www.vivabit.com/bollocks/2006/06/21/a-dom-ready-extension-for-prototype
* http://simon.incutio.com/archive/2004/05/26/addLoadEvent
*
*
* To use: call addDOMLoadEvent one or more times with functions, ie:
*
* function something() {
* // do something
* }
* addDOMLoadEvent(something);
*
* addDOMLoadEvent(function() {
* // do other stuff
* });
*
*/

addDOMLoadEvent = (function(){
// create event function stack
var load_events = [],
load_timer,
script,
done,
exec,
old_onload,
init = function () {
done = true;

// kill the timer
clearInterval(load_timer);

// execute each function in the stack in the order they were added
while (exec = load_events.shift())
exec();

if (script) script.onreadystatechange = '';
};

return function (func) {
// if the init function was already ran, just run this function now and stop
if (done) return func();

if (!load_events[0]) {
// for Mozilla/Opera9
if (document.addEventListener)
document.addEventListener("DOMContentLoaded", init, false);

// for Internet Explorer
/*@cc_on @*/
/*@if (@_win32)
document.write("<\/scr"+"ipt>");
script = document.getElementById("__ie_onload");
script.onreadystatechange = function() {
if (this.readyState == "complete")
init(); // call the onload handler
};
/*@end @*/

// for Safari
if (/WebKit/i.test(navigator.userAgent)) { // sniff
load_timer = setInterval(function() {
if (/loaded|complete/.test(document.readyState))
init(); // call the onload handler
}, 10);
}

// for other browsers set the window.onload, but also execute the old window.onload
old_onload = window.onload;
window.onload = function() {
init();
if (old_onload) old_onload();
};
}

load_events.push(func);
}
})();

二、另外还有在IE中的doScroll的，这是种方法只对IE有作用，而且它是一种hack方法。

在MSDN:About Element Behaviors 我们可以看到
代码如下:
When the ondocumentready event fires, the document has been completely parsed and built. Initialization code should be placed here if the component needs to navigate the primary document structure. The ondocumentready event notifies the component that the entire page is loaded, and it fires immediately before the onload event fires in the primary document.
A few methods, such as doScroll, require the primary document to be completely loaded. If these methods are part of an initialization function, they should be handled when the ondocumentready event fires.

http://javascript.nwbox.com/IEContentLoaded/
代码如下:
/*
*
* IEContentLoaded.js
*
* Author: Diego Perini (diego.perini at gmail.com) NWBOX S.r.l.
* Summary: DOMContentLoaded emulation for IE browsers
* Updated: 05/10/2007
* License: GPL/CC
* Version: TBD
*
*/

// @w window reference
// @fn function reference
function IEContentLoaded (w, fn) {
var d = w.document, done = false,
// only fire once
init = function () {
if (!done) {
done = true;
fn();
}
};
// polling for no errors
(function () {
try {
// throws errors until after ondocumentready
d.documentElement.doScroll('left');
} catch (e) {
setTimeout(arguments.callee, 50);
return;
}
// no errors, fire
init();
})();
// trying to always fire before onload
d.onreadystatechange = function() {
if (d.readyState == 'complete') {
d.onreadystatechange = null;
init();
}
};
}

在jQuery的源码中，针对Mozilla, Opera 和webkit用的是DOMContentLoaded，也就是上一篇中第一种；

而对IE用的是doScroll的方法。