判断 iframe 是否加载完毕

        //方法一、jQuery load()
	var frm = document.getElementById('myiframe');  
	$(frm).load(function(){                             //  等iframe加载完毕  
	dosomething();  
	});  
	 

	//方法二、onreadystatechange 
	var iframe = document.createElement("myiframe");  
	iframe.src = "http://www.baidu.com";  
	if (!/*@cc_on!@*/0) { //如果不是IE，IE的条件注释  
		iframe.onload = function(){     
			alert("Local iframe is now loaded.");  
		};  
	} else {  
		iframe.onreadystatechange = function(){ // IE下的节点都有onreadystatechange这个事件  
			if (iframe.readyState == "complete"){  
				alert("Local iframe is now loaded.");  
			}  
		};  
	}  
	document.body.appendChild(iframe);  
	 

	//方法三、attachEvent
	var iframe = document.createElement("iframe");  
	iframe.src = "http://www.baidu.com";  
	  
	if (iframe.attachEvent){  
		iframe.attachEvent("onload", function(){ // IE  
			alert("Local iframe is now loaded.");  
		});  
	} else {  
		iframe.onload = function(){ // 非IE  
			alert("Local iframe is now loaded.");  
		};  
	}  
	document.body.appendChild(iframe);