var ajax = false;

if (window.XMLHttpRequest) {
	ajax = new XMLHttpRequest();
} else if (window.ActiveXObject) {
	try {
		ajax = new ActiveXObject("Msxml2.XMLHTTP");
	} catch (e1) {
		try { 
			ajax = new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e2) { }
	}
}
if(!ajax) {
	alert ('Some page functionality does not work on your browser.');
}