var request = false;
try {request = new XMLHttpRequest();}
   catch (trymicrosoft)
    {
    try {request = new ActiveXObject("Msxml2.XMLHTTP");}
    catch (othermicrosoft)
      {
      try {request = new ActiveXObject("Microsoft.XMLHTTP");}
	  catch (failed) {request = false;}  
      }
    }
if (!request)
  alert("Error initializing XMLHttpRequest!");