var request = null

if (window.XMLHttpRequest && !(window.ActiveXObject)) {
    try {
        request = new XMLHttpRequest();
    } catch (e) {
    }
} else if (window.ActiveXObject) {
    /* branch for IE/Windows ActiveX version */
        try {
        request = new ActiveXObject("Msxml2.XMLHTTP");
    } catch (e) {
        try {
            request = new ActiveXObject("Microsoft.XMLHTTP");
        } catch(e) {
        }
    }
}