JavaScript创建通用XMLHttpRequest对象

function createXmlHttpRequestObject()
{
        if (window.XMLHttpRequest)   
        {    xmlhttp_request = new XMLHttpRequest();    }
            else
            {    var MSXML=['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
                for(var n = 0; n < MSXML.length; n ++)
                {   
                    try  
                     {   
                     xmlhttp_request = new ActiveXObject(MSXML[n]); 
                       break; 
                     }
                    catch(e){}
                }
            }

}