AJAX异步刷新

k=setTimeout("test_username()",2000);//调用AJAX中的test_username（）方法


//AJAX异步刷新
var xmlhttp;var time=0;
function type_browser(){
    xmlhttp = false;
    xmlhttpObj = ["MSXML2.XmlHttp.5.0","MSXML2.XmlHttp.4.0","MSXML2.XmlHttp.3.0","MSXML2.XmlHttp","Microsoft.XmlHttp"];
    if(window.XMLHttpRequest)
    {
        xmlhttp = new XMLHttpRequest();
    }
    else if(window.ActiveXObject)
    {
        for(i=0;i<xmlhttpObj.length;i++) 
        {
            xmlhttp = new ActiveXObject(xmlhttpObj);
            if(xmlhttp)
            {
                break; 
            }
        }
    }
    else
    {
        alert("暂时不能创建XMLHttpRequest对象");
    }
    return xmlhttp?xmlhttp:false;
}
function test_username(){

    type_browser();
    //var username=document.userform.username.value;
    xmlhttp.open("POST","<?=site_url('zpz/index2')?>",true);

    xmlhttp.onreadystatechange=getdata;
    xmlhttp.send();
    k=setTimeout("test_username()",2000); 
}
function getdata(){
    var data=xmlhttp.responseText;
    //document.getElementById('tbody').innerHTML=null;
    document.getElementById('tbody').innerHTML=data;
    document.getElementById('test11').innerHTML=time;
    time++;
}