完美判断iframe是否加载

var iframe = document.createElement("iframe");iframe.style.width = "265px";iframe.style.height = "490px";iframe.style.border = "none";iframe.src = "http://cnblogs.com/walls";        if(iframe.attachEvent){     //IE     iframe.attachEvent("onload", function(){         alert("loaded 1");     });}else{     iframe.onload = function(){         console.log("loaded 2");     };}