用Ajax读取XML格式的数据

!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 
html> 
head> 
title>Ajax Hello World/title> 
script type="text/javascript"> 
var xmlHttp; 

function createXMLHttpRequest(){ 
    if(window.ActiveXObject){ 
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); 
    } 
    else if(window.XMLHttpRequest){ 
        xmlHttp = new XMLHttpRequest(); 
    } 
} 

function startRequest(){ 
    createXMLHttpRequest(); 
    try{ 
        xmlHttp.onreadystatechange = handleStateChange; 
        xmlHttp.open("GET", "data.xml", true); 
        xmlHttp.send(null);     
    }catch(exception){ 
        alert("您要访问的资源不存在!"); 
    } 
} 

function handleStateChange(){     
    if(xmlHttp.readyState == 4){         
        if (xmlHttp.status == 200 || xmlHttp.status == 0){ 
            // 取得XML的DOM对象 
            var xmlDOM = xmlHttp.responseXML; 
            // 取得XML文档的根 
            var root = xmlDOM.documentElement;             
            try 
            { 
                // 取得info>结果 
                var info = root.getElementsByTagName('info'); 
                // 显示返回结果 
                alert("responseXML's value: " + info[0].firstChild.data); 
            }catch(exception) 
            { 

            } 
        } 
    } 
} 
/script> 
/head> 
body> 
    div> 
        input type="button" value="return ajax responseXML's value" 
                onclick="startRequest();" /> 
    /div> 
/body> 
/html>

?xml version="1.0" encoding="GB2312" ?> 
root>
    info>hello world!/info>
/root>