function getResponse(adr, callback, timeoutCallback = function(){alert("timeout error. Please reload the site");}, timeout = 3000){
	var xmlhttp = new XMLHttpRequest();
	xmlhttp.onreadystatechange = function() {
		if(xmlhttp.readyState == 4){
	    if(xmlhttp.status == 200) callback(xmlhttp.responseText);
			else timeoutCallback();
		}
	};
	xmlhttp.open("GET", adr, true);
	xmlhttp.send();
	xmlhttp.timeout = timeout;
  xmlhttp.ontimeout = timeoutCallback;
}