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!");}