JS DOMReady事件的六种实现方法总结

(function() {

var timer;

function fireContentLoadedEvent() {

if (document.loaded) return;

if (timer) window.clearInterval(timer);

document.fire("dom:loaded");

document.loaded = true;

}

if (document.addEventListener) {

if (Prototype.Browser.WebKit) {

timer = window.setInterval(function() {

if (/loaded|complete/.test(document.readyState))

fireContentLoadedEvent();

}, 0);

Event.observe(window, "load", fireContentLoadedEvent);

} else {

document.addEventListener("DOMContentLoaded",

fireContentLoadedEvent, false);

}

} else {

document.write("<"+"script id=__onDOMContentLoaded defer src=//:><\/script>");

$("__onDOMContentLoaded").onreadystatechange = function() {

if (this.readyState == "complete") {

this.onreadystatechange = null;

fireContentLoadedEvent();

}

};

}

})();

function bindReady(){

if ( readyBound ) return;

readyBound = true;

// Mozilla, Opera and webkit nightlies currently support this event

if ( document.addEventListener ) {

// Use the handy event callback

document.addEventListener( "DOMContentLoaded", function(){

document.removeEventListener( "DOMContentLoaded", arguments.callee, false );

jQuery.ready();

}, false );

// If IE event model is used

} else if ( document.attachEvent ) {

// ensure firing before onload,

// maybe late but safe also for iframes

document.attachEvent("onreadystatechange", function(){

if ( document.readyState === "complete" ) {

document.detachEvent( "onreadystatechange", arguments.callee );

jQuery.ready();

}

});

// If IE and not an iframe

// continually check to see if the document is ready

if ( document.documentElement.doScroll && typeof window.frameElement === "undefined" ) (function(){

if ( jQuery.isReady ) return;

try {

// If IE is used, use the trick by Diego Perini

// http://javascript.nwbox.com/IEContentLoaded/

document.documentElement.doScroll("left");

} catch( error ) {

setTimeout( arguments.callee, 0 );

return;

}

// and execute any waiting functions

jQuery.ready();

})();

}

// A fallback to window.onload, that will always work

jQuery.event.add( window, "load", jQuery.ready );

}

(function(){
 
var domready = function(){
 
if (Browser.loaded) return;
 
Browser.loaded = true;
 
window.fireEvent('domready');
 
document.fireEvent('domready');
 
};
 
if (Browser.Engine.trident){
 
var temp = document.createElement_x('div');
 
(function(){
 
($try(function(){
 
temp.doScroll('left');
 
return $(temp).inject(document.body).set('html', 'temp').dispose();
 
})) ? domready() : arguments.callee.delay(50);
 
})();
 
} else if (Browser.Engine.webkit && Browser.Engine.version < 525){
 
(function(){
 
(['loaded', 'complete'].contains(document.readyState)) ? domready() : arguments.callee.delay(50);
 
})();
 
} else {
 
window.addEvent('load', domready);
 
document.addEvent('DOMContentLoaded', domready);
 
}
 
})();

// START DOMContentLoaded
 
// Mozilla and Opera 9 expose the event we could use
 
if(document.addEventListener){
 
// NOTE:
 
// due to a threading issue in Firefox 2.0, we can't enable
 
// DOMContentLoaded on that platform. For more information, see:
 
// http://trac.dojotoolkit.org/ticket/1704
 
if(dojo.isOpera || dojo.isFF >= 3 || (dojo.isMoz && dojo.config.enableMozDomContentLoaded === true)){
 
document.addEventListener("DOMContentLoaded", dojo._loadInit, null);
 
}
 
// mainly for Opera 8.5, won't be fired if DOMContentLoaded fired already.
 
// also used for Mozilla because of trac #1640
 
window.addEventListener("load", dojo._loadInit, null);
 
}
 
if(dojo.isAIR){
 
window.addEventListener("load", dojo._loadInit, null);
 
}else if(/(WebKit|khtml)/i.test(navigator.userAgent)){ // sniff
 
dojo._khtmlTimer = setInterval(function(){
 
if(/loaded|complete/.test(document.readyState)){
 
dojo._loadInit(); // call the onload handler
 
}
 
}, 10);
 
}
 
// END DOMContentLoaded
 
}
 
(function(){
 
var _w = window;
 
var _handleNodeEvent = function(evtName, fp){
 
// summary:
 
// non-destructively adds the specified function to the node's
 
// evtName handler.
 
// evtName: should be in the form "onclick" for "onclick" handlers.
 
// Make sure you pass in the "on" part.
 
var oldHandler = _w[evtName] || function(){};
 
_w[evtName] = function(){
 
fp.apply(_w, arguments);
 
oldHandler.apply(_w, arguments);
 
};
 
};
 
if(dojo.isIE){
 
// for Internet Explorer. readyState will not be achieved on init
 
// call, but dojo doesn't need it however, we'll include it
 
// because we don't know if there are other functions added that
 
// might. Note that this has changed because the build process
 
// strips all comments -- including conditional ones.
 
if(!dojo.config.afterOnLoad){
 
document.write('<scr'+'ipt defer="" src="//:" +="" onreadystatechange="if(this.readyState==\'complete\'){' + 
 
dojo._scopeName + '._loadInit();}">'
 
+ '</scr'+'ipt>'
 
);
 
}
 
try{
 
document.namespaces.add("v","urn:schemas-microsoft-com:vml");
 
document.createStyleSheet().addRule("v\\:*", "behavior:url(#default#VML)");
 
}catch(e){}
 
}
 
// FIXME: dojo.unloaded requires dojo scope, so using anon function wrapper.
 
_handleNodeEvent("onbeforeunload", function() { dojo.unloaded(); });
 
_handleNodeEvent("onunload", function() { dojo.windowUnloaded(); });
 
})();

// Internet Explorer: use the readyState of a defered script.
 
// This isolates what appears to be a safe moment to manipulate
 
// the DOM prior to when the document's readyState suggests
 
// it is safe to do so.
 
if (EU.isIE) {
 
// Process onAvailable/onContentReady items when the
 
// DOM is ready.
 
YAHOO.util.Event.onDOMReady(
 
YAHOO.util.Event._tryPreloadAttach,
 
YAHOO.util.Event, true);
 
var n = document.createElement_x('p');
 
EU._dri = setInterval(function() {
 
try {
 
// throws an error if doc is not ready
 
n.doScroll('left');
 
clearInterval(EU._dri);
 
EU._dri = null;
 
EU._ready();
 
n = null;
 
} catch (ex) {
 
}
 
}, EU.POLL_INTERVAL);
 
// The document's readyState in Safari currently will
 
// change to loaded/complete before images are loaded.
 
} else if (EU.webkit && EU.webkit < 525) {
 
EU._dri = setInterval(function() {
 
var rs=document.readyState;
 
if ("loaded" == rs || "complete" == rs) {
 
clearInterval(EU._dri);
 
EU._dri = null;
 
EU._ready();
 
}
 
}, EU.POLL_INTERVAL);
 
// FireFox and Opera: These browsers provide a event for this
 
// moment. The latest WebKit releases now support this event.
 
} else {
 
EU._simpleAdd(document, "DOMContentLoaded", EU._ready);
 
}
 
/////////////////////////////////////////////////////////////
 
EU._simpleAdd(window, "load", EU._load);
 
EU._simpleAdd(window, "unload", EU._unload);
 
EU._tryPreloadAttach();
 
})();

function initDocReady(){
 
var COMPLETE = "complete";
 
docReadyEvent = new Ext.util.Event();
 
if (Ext.isGecko || Ext.isOpera) {
 
DOC.addEventListener(DOMCONTENTLOADED, fireDocReady, false);
 
} else if (Ext.isIE){
 
DOC.write("<s"+'cript id=" + IEDEFERED + " defer="defer" src="/'+'/:"></s"+'cript>");
 
DOC.getElementById(IEDEFERED).onreadystatechange = function(){
 
if(this.readyState == COMPLETE){
 
fireDocReady();
 
}
 
};
 
} else if (Ext.isWebKit){
 
docReadyProcId = setInterval(function(){
 
if(DOC.readyState == COMPLETE) {
 
fireDocReady();
 
}
 
}, 10);
 
}
 
// no matter what, make sure it fires on load
 
E.on(WINDOW, "load", fireDocReady);
 
};

function onDOMContentLoaded(onready,config){
 
//浏览器检测相关对象，在此为节省代码未实现，实际使用时需要实现。
 
//var Browser = {};
 
//设置是否在FF下使用DOMContentLoaded（在FF2下的特定场景有Bug）
 
this.conf = {enableMozDOMReady:true};
 
if( config )
 
for( var p in config)
 
this.conf[p] = config[p];
 
var isReady = false;
 
function doReady(){
 
if( isReady ) return;
 
//确保onready只执行一次
 
isReady = true;
 
onready();
 
}
 
 
if( Browser.ie ){
 
(function(){
 
if ( isReady ) return;
 
try {
 
document.documentElement.doScroll("left");
 
} catch( error ) {
 
setTimeout( arguments.callee, 0 );
 
return;
 
}
 
doReady();
 
})();
 
window.attachEvent('onload',doReady);
 
}
 
 
else if (Browser.webkit && Browser.version < 525){
 
(function(){
 
if( isReady ) return;
 
if (/loaded|complete/.test(document.readyState))
 
doReady();
 
else
 
setTimeout( arguments.callee, 0 );
 
})();
 
window.addEventListener('load',doReady,false);
 
}
 
 
else{
 
if( !Browser.ff || Browser.version != 2 || this.conf.enableMozDOMReady)
 
document.addEventListener( "DOMContentLoaded", function(){
 
document.removeEventListener( "DOMContentLoaded", arguments.callee, false );
 
doReady();
 
}, false );
 
window.addEventListener('load',doReady,false);
 
}
 
}