DOMReady.js

/*
---

name: DOMReady

description: Contains the custom event domready.

license: MIT-style license.

requires: [Browser, Element, Element.Event]

provides: [DOMReady, DomReady]

...
*/

(function(window, document){

var ready,
	loaded,
	checks = [],
	shouldPoll,
	timer,
	testElement = document.createElement('div');

var domready = function(){
	clearTimeout(timer);
	if (!ready) {
		Browser.loaded = ready = true;
		document.removeListener('DOMContentLoaded', domready).removeListener('readystatechange', check);
		document.fireEvent('domready');
		window.fireEvent('domready');
	}
	// cleanup scope vars
	document = window = testElement = null;
};

var check = function(){
	for (var i = checks.length; i--;) if (checks[i]()){
		domready();
		return true;
	}
	return false;
};

var poll = function(){
	clearTimeout(timer);
	if (!check()) timer = setTimeout(poll, 10);
};

document.addListener('DOMContentLoaded', domready);

/*<ltIE8>*/
// doScroll technique by Diego Perini http://javascript.nwbox.com/IEContentLoaded/
// testElement.doScroll() throws when the DOM is not ready, only in the top window
var doScrollWorks = function(){
	try {
		testElement.doScroll();
		return true;
	} catch (e){}
	return false;
};
// If doScroll works already, it can't be used to determine domready
//   e.g. in an iframe
if (testElement.doScroll && !doScrollWorks()){
	checks.push(doScrollWorks);
	shouldPoll = true;
}
/*</ltIE8>*/

if (document.readyState) checks.push(function(){
	var state = document.readyState;
	return (state == 'loaded' || state == 'complete');
});

if ('onreadystatechange' in document){
	document.addListener('readystatechange', check);
	var state = document.readyState;
	if (state == 'loaded' || state == 'complete') domready();
}
else shouldPoll = true;

if (shouldPoll) poll();

Element.Events.domready = {
	onAdd: function(fn){
		if (ready) fn.call(this);
	}
};

// Make sure that domready fires before load
Element.Events.load = {
	base: 'load',
	onAdd: function(fn){
		if (loaded && this == window) fn.call(this);
	},
	condition: function(){
		if (this == window){
			domready();
			delete Element.Events.load;
		}
		return true;
	}
};

// This is based on the custom load event
window.addEvent('load', function(){
	loaded = true;
});

})(window, document);