var xmlHttp = null; {
            try {
                // Firefox, Opera 8.0+, Safari, IE7+
                xmlHttp = new XMLHttpRequest();
            } catch (e) {
                // Internet Explorer
                try {
                    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
                } catch (e) {
                    xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
                }
            }
        }