AJAX

lluorongsheng

if(trim(field.value).length != 0) {//-------------------创建浏览器对象---------------------------var xmlHttp = null;//表示当前浏览器不是ie,如ns,firefoxif(window.XMLHttpRequest) {xmlHttp = new XMLHttpRequest();} else if (window.ActiveXObject) {xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");}//-------------------创建浏览器对象---------------------------var url = "user_validate.jsp?userId="+trim(field.value)+"&time=" + new Date().getTime();//设置请求方式为GET,设置请求的URL,设置为异步提交xmlHttp.open("GET", url, true);//true表示的是异步//将方法地址复制给oneadystatechange属性//类似于电话号码//=======================================匿名函数xmlHttp.onreadystatechange=function() {//alert(xmlHttp.readyState);//Ajax引擎状态为成功if(xmlHttp.readyState == 4) {//HTTP协议状态成功if(xmlHttp.status == 200) {if(trim(xmlHttp.responseText) != "") {//alert(xmlHttp.responseText);document.getElementById("spanUserId").innerHTML = "<font color = 'red'>" + xmlHttp.responseText + "</font>";} else {document.getElementById("spanUserId").innerHTML = "";}} else {alert("请求失败,错误码=" + xmlHttp.status);}}};//将设置信息发送到Ajax引擎xmlHttp.send(null);} else {document.getElementById("spanUserId").innerHTML = "";}