ajax实现点击不同的链接让返回的内容显示在特定div里

html> 
head> 
meta charset="UTF-8"> 
title>Insert title here/title> 
script language="javascript"> 
var http_request = false; 
function createRequest(url,objID){ 
http_request = false; 
if(window.XMLHttpRequest){ //非IE浏览器 
http_request = new XMLHttpRequest(); 
if(http_request.overrideMimeType){ 
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){ 
alert("无法创建XMLHTTP实例"); 
return false; 
} 
http_request.open("GET",url,true); 
http_request.send(null); 

var obj = document.getElementById(objID); 
http_request.onreadystatechange = function(){ 
if(http_request.readyState == 4){ 
if(http_request.status == 200){ 
obj.innerHTML = http_request.responseText; 
}else{ 
alert('您请求的页面发现错误！'); 
} 
} 
} 
} 
/script> 
/head> 

body onload="createRequest('content1.html','show')"> 
div align="center"> 
a href="content1.html" onclick="createRequest('content1.html','show');return false;">no1/a> | 
a href="content2.html" onclick="createRequest('content2.html','show');return false;">no2/a> | 
a href="content3.html" onclick="createRequest('content3.html','show');return false;">no3/a> 
/div> 
div id="show" align="center">/div> 
/body> 
/html>