var http_request = false;
http_request = false;

if (window.XMLHttpRequest) { // Mozilla, Safari,...
	http_request = new XMLHttpRequest();
    if (http_request.overrideMimeType) {
    	http_request.overrideMimeType('text/xml');
	}
} else if (window.ActiveXObject) { // IE
	try {
		http_request = new ActiveXObject("Msxml2.XMLHTTP");
	} catch (e) {
		try {
			http_request = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
		}
}
if (!http_request) {
	alert('Giving up :( Cannot create an XMLHTTP instance');
}