var request = null;

try{
	request = new XMLHttpRequest(); // Mozilla, Safari, Opera
}
catch(trymicrosoft)
{
	try{
		request = new ActiveXObject("Msxml2.XMLHTTP"); // For Old Microsoft Browsers
	} 
	catch(othermicrosoft)
	{
		try{
			request = new ActiveXObject("Microsoft.XMLHTTP"); // For Microsoft IE 6.0+
		}
		catch(failed){
			request = null; // No Browser accepts the XMLHTTP Object then false
		}
	}
}

if(request == null)
	alert("Your browser does not support Ajax HTTP!");