function getXMLHTTPRequest()
        {
        try
            {
            req = new XMLHttpRequest(); /*e.g. FireFox*/
            }
        catch(err1)
            {
            try
                {
                req = new ActiveXObject("Msxm12.XMLHTTP");/*some I.E. versions*/
                }
            catch(err2)
                {
                try
                    {
                    req = new ActiveXObject("Microsoft.XMLHTTP");/*other I.E. versions*/
                    }
                catch(err3)
                    {
                    req = false;
                    }
                }
            }
        return req;
        }
    var http = getXMLHTTPRequest();
    //alert("http ="+http.readyState);