比Jquery的document.ready更快的方法

var jb51 =new function() { 
dom = []; 
dom.isReady = false; 
dom.isFunction = function(obj) { 
return Object.prototype.toString.call(obj) === "[object Function]"; 
} 
dom.Ready = function(fn) { 
dom.initReady(); 
//如果没有建成DOM树，则走第二步，存储起来一起杀 
if (dom.isFunction(fn)) { 
if (dom.isReady) { 
fn(); 
//如果已经建成DOM，则来一个杀一个 
} else { 
dom.push(fn); 
//存储加载事件 
} 
} 
} 
dom.fireReady = function() { 
if (dom.isReady) return; 
dom.isReady = true; 
for (var i = 0, n = dom.length; i < n; i++) { 
var fn = dom[i]; 
fn(); 
} 
dom.length = 0; 
//清空事件 
} 
dom.initReady = function() { 
if (document.addEventListener) { 
document.addEventListener("DOMContentLoaded", 
function() { 
document.removeEventListener("DOMContentLoaded", arguments.callee, false); 
//清除加载函数 
dom.fireReady(); 
}, 
false); 
} else { 
if (document.getElementById) { 
document.write("<script id=\"ie-domReady\" defer='defer'src=\"//:\"><\/script>"); 
document.getElementById("ie-domReady").onreadystatechange = function() { 
if (this.readyState === "complete") { 
dom.fireReady(); 
this.onreadystatechange = null; 
this.parentNode.removeChild(this) 
} 
}; 
} 
} 
} 
}