// JavaScript Document
function CreateXHR()
{
	var request;
	var browser = navigator.appName;
	//使用IE，则使用XMLHttp对象
	if(browser == "Microsoft Internet Explorer")
	{
		var arrVersions = ["Microsoft.XMLHttp", "MSXML2.XMLHttp.4.0",
		  "MSXML2.XMLHttp.3.0", "MSXML2.XMLHttp","MSXML2.XMLHttp.5.0"];
		for (var i=0; i < arrVersions.length; i++)
		{
		  try
		  {
	//从中找到一个支持的版本并建立XMLHttp对象
			request = new ActiveXObject(arrVersions[i]);
			return request;
		  }
		  catch(exception)
		  {
			 //忽略，继续
		  }
		}
	}
	else
	{
		//否则返回一个XMLHttpRequest对象
		request = new XMLHttpRequest();
		if(request.overrideMimeType)
		{
	　　 request.overrideMimeType('text/xml;charset=utf-8');
	　 }
		return request;
	}  
}