var xmlRequest;
    var gourl;
    function xmlRequest() {

        try {
            xmlRequest = new ActiveXObject("Microsoft.XMLHTTP");
        }
        catch (err) {
            xmlRequest = new ActiveXObject("Microsoft.XMLHTTP");
        }
        gourl = "http://www.baidu.com/121212";
        alert(gourl);
        xmlRequest.open("get", gourl, true);
        xmlRequest.onreadystatechange = goback; //回调函数
        xmlRequest.send();
    }
    function goback() {


        if (xmlRequest.readyState == 4) {
            debugger
            if (xmlRequest.status == 200 || xmlRequest.status == 0) {
                //处理数据
                //........
                alert(xmlRequest.status);
            }
            alert(xmlRequest.status);
        }

    }