var request = null;
createRequest();

function createRequest() {
	try {
		request = new XMLHttpRequest();
	} catch (trymicrosoft) {
	  try {
		request = new ActiveXObject("Mxml2.XMLHTTP");
	} catch (othermicrosoft) {
	  try {
		request = new ActiveXObject("Microsoft.XMLHTTP");
	} catch (failed) {
		request = null;
	}
	}
}
  if (request==null)
	alert("Error creating XML request!");
}