Mine

 if (window.XMLHttpRequest) { // Mozilla, Safari,...         http_request = new XMLHttpRequest();         if (http_request.overrideMimeType) {            http_request.overrideMimeType('text/xml');         }      } else if (window.ActiveXObject) { // IE         try {            http_request = new ActiveXObject("Msxml2.XMLHTTP");         } catch (e) {            try {               http_request = new ActiveXObject("Microsoft.XMLHTTP");            } catch (e) {}         }      }      if (!http_request) {         alert('Cannot create XMLHTTP instance');         return false;      }