function getXMLHttpRequest(){
//alert()
if(navigator.userAgent.toLowerCase().indexOf("msie")>-1){//жǷIE
 var MSXML=["Msxml2.XMLHTTP.5.0","Msxml2.XMLHTTP.4.0","Msxml2.XMLHTTP.3.0","Msxml2.XMLHTTP","Microsoft.XMLHTTP"]
 for(i=0;i<MSXML.length;i++){
   try{

     return new ActiveXObject(MSXML[i])
	}catch(e){

	}	
 }
 return null
 }
 if(navigator.userAgent.toLowerCase().indexOf("firefox")>-1){//Ϊfirefox
   return document.implementation.createDocument("", "doc", null);
 }
}