var http_request=null; function create_ajax(){     http_request = false;     //开始初始化XMLHttpRequest对象     if(window.XMLHttpRequest) { //Mozilla 浏览器         http_request = new XMLHttpRequest();         if (http_request.overrideMimeType) {//设置MiME类别             http_request.overrideMimeType('text/xml');         }     }     else if (window.ActiveXObject) { // IE浏览器         try {             http_request = new ActiveXObject("Msxml2.XMLHTTP");         } catch (e) {             try {                 http_request = new ActiveXObject("Microsoft.XMLHTTP");             } catch (e) {}         }     }     if (!http_request) { // 异常，创建对象实例失败         window.alert("不能创建XMLHttpRequest对象实例.");         return false;     } }

var obj1; function get_ajax(url,obj) {//初始化、指定处理函数、发送请求的函数 obj1=obj; create_ajax(); http_request.onreadystatechange =processobj; // 确定发送请求的方式和URL以及是否同步执行下段代码 http_request.open("POST", url, true); http_request.send(null); } function processobj(){ document.getElementById(obj1).innerHTML="Loading..."; if (http_request.readyState == 4) { // 判断对象状态 if (http_request.status == 200) { // 信息已经成功返回，开始处理信息 document.getElementById(obj1).innerHTML=http_request.responseText; } else { //页面不正常 document.getElementById(obj1).innerHTML="loading error."; } } }

<script type="text/javascript" src="ajax.js" src="ajax.js" ></script> Welcome. <div id="d1" onclick="get_ajax('ajax/get1.jsp','d1');">d1</div> <div id="d2" onclick="get_ajax('ajax/get2.jsp','d2');">d2</div> <div id="a">d2</div>