js写ajax

ajax无刷新技术(异步通讯技术)

new XMLHTTPRequest

//ajax

function new_ajax(url,success,fail){//1.创建ajax对象        if(window.XMLHttpRequest){//兼容非IE6P                var oAjax=new XMLHttpRequest();        }else{//IE6                var oAjax=new ActiveXObject("Microsoft.XMLHTTP");       }        //2.链接服务器        //open(方法,文件名,异步传输)       oAjax.open('GET',url,true);        //3.发送请求        oAjax.send();        //4.接收返回值        oAjax.onreadystatechange=function(){//oAjax.readyState浏览器和服务器交互到哪一步        //0未初始化，还没有调用open()        //1载入,已调用send()方法，正在发送请求        //2载入完成        //3解析        //4完成，成败都会        if(oAjax.readyState==4)//读取完成        {            if(oAjax.status==200)//成功            {                       success(oAjax.responseText);                }else{                       fail(oAjax.status);                }            }        };}