从w3school中获取代码
<html>
<head>
<script type="text/javascript">
var xmlhttp;
function loadXMLDoc(url)
{
xmlhttp=null;
if (window.XMLHttpRequest)
{// code for IE7, Firefox, Opera, etc.
xmlhttp=new XMLHttpRequest();
}
else if (window.ActiveXObject)
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
if (xmlhttp!=null)
{
xmlhttp.onreadystatechange=state_Change;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}
else
{
alert("Your browser does not support XMLHTTP.");
}
} function state_Change()
{
if (xmlhttp.readyState==4)
{// 4 = "loaded"
if (xmlhttp.status==200)
{// 200 = "OK"
document.getElementById('A1').innerHTML=xmlhttp.status;
document.getElementById('A2').innerHTML=xmlhttp.statusText;
document.getElementById('A3').innerHTML=xmlhttp.responseText;
}
else
{
alert("Problem retrieving XML data:" + xmlhttp.statusText);
}
}
}
</script>
</head> <body>
<h2>Using the HttpRequest Object</h2> <p><b>Status:</b>
<span id="A1"></span>
</p> <p><b>Status text:</b>
<span id="A2"></span>
</p> <p><b>Response:</b>
<br /><span id="A3"></span>
</p> <button onclick="loadXMLDoc('/demo.xml')">Get XML</button> </body>
</html>
关键是xmlhttprequest对象的创建，以及xml路径的传递，以及返回的内容
注意，返回结果直接是xml节点内容、
xml内容如下：
<note time="16:06:03">
<to>George</to>
<from>John</from>
<heading>Reminder</heading>
<body>Don't forget the meeting!</body>
</note>
返回结果如下：
