var iframe = document.createElement("iframe"); 
iframe.src = "http://www.jb51.net";

if (!/*@cc_on!@*/0) { //if not IE 
iframe.onload = function(){ 
alert("Local iframe is now loaded."); 
}; 
} else { 
iframe.onreadystatechange = function(){ 
if (iframe.readyState == "complete"){ 
alert("Local iframe is now loaded."); 
} 
}; 
} 
document.body.appendChild(iframe); 

 

 

 

（很完美）
var iframe = document.createElement("iframe"); 
iframe.src = "http://sc.jb51.net"; 
if (iframe.attachEvent){ 
iframe.attachEvent("onload", function(){ 
alert("Local iframe is now loaded."); 
}); 
} else { 
iframe.onload = function(){ 
alert("Local iframe is now loaded."); 
}; 
} 
document.body.appendChild(iframe);