判断 iframe 是否加载完成的完美方法

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

另外的一种方法:

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

摘自于<<悍飞>>的博客:http://www.planabc.net/2009/09/22/iframe_onload/