判断加载iframe成功的较好的方式

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.");
    };
}

忘记从哪看的了。。。没法写转载地址了。。。确实onreadystatechange有时候是有问题的