IE和FireFox下通用的js操作xml代码

http://hi.baidu.com/%B1%B1%CF%C0%C5%B7%D1%F4%CB%BC%B4%BA/blog/item/a0f87c3643a6ca350a55a910.html

<script>
var XmlReader = function(){
this.GetHttpRequest = function(){
if (window.XMLHttpRequest) // Gecko
return new XMLHttpRequest();
else if (window.ActiveXObject) // IE
return new ActiveXObject("MsXml2.XmlHttp") ;
}
this.LoadUrl = function(urlToCall, asyncFunctionPointer){
var oXmlReader = this;
var bAsync = (typeof(asyncFunctionPointer) == "function");

var oXmlHttp = this.GetHttpRequest();
oXmlHttp.open("GET", urlToCall, bAsync);
if (bAsync){
oXmlHttp.onreadystatechange = function()
{
if (oXmlHttp.readyState == 4){
oXmlReader.DOMDocument = oXmlHttp.responseXML;
if (oXmlHttp.status == 200)
asyncFunctionPointer( oXmlReader ) ;
else
alert("XML request error: " + oXmlHttp.statusText + " (" + oXmlHttp.status + ")" ) ;
}
}
}

oXmlHttp.send(null) ;

if (!bAsync)
{
if (oXmlHttp.status == 200)
this.DOMDocument = oXmlHttp.responseXML ;
else
{
alert("XML request error: " + oXmlHttp.statusText + " (" + oXmlHttp.status + ")") ;
}
}
}
this.SelectNodes = function(xpath){
if (document.all) // IE
return this.DOMDocument.selectNodes(xpath) ;
else{ // Gecko
var aNodeArray = new Array();

var xPathResult = this.DOMDocument.evaluate(xpath, this.DOMDocument, this.DOMDocument.createNSResolver(this.DOMDocument.documentElement), XPathResult.ORDERED_NODE_ITERATOR_TYPE, null) ;
if (xPathResult){
var oNode = xPathResult.iterateNext() ;
while(oNode){
aNodeArray[aNodeArray.length] = oNode ;
oNode = xPathResult.iterateNext();
}
}
return aNodeArray ;
}
}
this.SelectSingleNode = function(xpath){
if (document.all) // IE
return this.DOMDocument.selectSingleNode( xpath ) ;
else{ // Gecko
var xPathResult = this.DOMDocument.evaluate( xpath, this.DOMDocument,
this.DOMDocument.createNSResolver(this.DOMDocument.documentElement), 9, null);

if (xPathResult && xPathResult.singleNodeValue)
return xPathResult.singleNodeValue ;
else
return null ;
}
}
}

</script>