function createRequest() {
  try {
        request = new XMLHttpRequest();
      } catch (trymicrosoft) {
        try {
              request = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (othermicrosoft) {
          try {
                request = new ActiveXObject("Microsoft.XMLHTTP");
          } catch (failed) {
            request = null;
          }
        }
      }

  if (request == null)
    alert("Error creating request object!");   
  else
    return request;
}