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

if (!/*@cc_on!@*/0) { //if not IE
    iframe.onload = function(){
        alert("框架加载完毕.");
    };
} else {
    iframe.onreadystatechange = function(){
        if (iframe.readyState == "complete"){
            alert("框架加载完毕.");
        }
    };
}

document.body.appendChild(iframe);

//方法二
var iframe = document.createElement("iframe");
iframe.src = "http://www.baidu.com/";

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);