xmlhttp创建方法并发送数据检测返回信息

function start_sel(murl,furl,g,res_){
 var url = "checkServer.php";
 var oBao = CreateHTTPObject();
 oBao.open("POST",url,true);
 oBao.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
 var res = document.getElementById(res_);
 oBao.onreadystatechange = function () { OnReadyStateChng(res,oBao);};
 oBao.send("m="+murl+"&f="+furl+"&g="+g);
 //oBao = null;
}

function OnReadyStateChng(res,xmlhttp) {
    if (xmlhttp.readyState == 4) {
        if (xmlhttp.status == 200) {
            res.innerHTML = unescape(xmlhttp.responseText);
        }
        else {
            //alert("HTTP 错误,错误代码:" + xmlhttp.status);
   res.innerHTML = "失败,<a href='javascript:;' onclick='checkRep(this);'>重新检测</a>";
        }
    }else{
  res.innerHTML = "<img class=loading src='images/loading.gif'>";
 }
}

function CreateHTTPObject(){
    var xmlhttp;
   
    try {
        xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e) {
        try {
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
        catch (e) {
            xmlhttp = false;
        }
    }
   
    if (!xmlhttp && typeof XMLHttpRequest!='undefined') {
        try {
            xmlhttp = new XMLHttpRequest();
        }
        catch (e) {
            xmlhttp=false;
        }
    }
   
    if (!xmlhttp && window.createRequest) {
        try {
            xmlhttp = window.createRequest();
        }
        catch (e) {
            xmlhttp=false;
        }
    }
   
    return xmlhttp;
}