var xmlhttp = false;
        // Mozilla/Safari
        if (window.XMLHttpRequest) {
            xmlhttp = new XMLHttpRequest();
            if (xmlhttp.overrideMimeType) {
                xmlhttp.overrideMimeType('text/xml');
                // See note below about this line
            }
        // IE
        } else if (window.ActiveXObject) { // IE
            try {
               xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try {
               xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
            }
        }