var XMLHttpRequestObject = false; 
      try { 
          XMLHttpRequestObject = new ActiveXObject("MSXML2.XMLHTTP"); 
      } catch (exception1) { 
          try { 
              XMLHttpRequestObject = new ActiveXObject("Microsoft.XMLHTTP"); 
          } catch (exception2) { 
              XMLHttpRequestObject = false; 
          } 
      } 

      if (!XMLHttpRequestObject && window.XMLHttpRequest) { 
        XMLHttpRequestObject = new XMLHttpRequest(); 
      }