function Check_Auction(max_id,user_id)
{
	// verbinding maken
	if (window.ActiveXObject) 
	{
		var http = new ActiveXObject("Microsoft.XMLHTTP");
	}
	else if (window.XMLHttpRequest) 
	{
	    var http = new XMLHttpRequest();
	}

	http.open('get', '/check_auction.php?id='+max_id+'&user_id='+user_id+'&rnd='+Math.round(1000000*Math.random()),true);
	http.onreadystatechange = function() {
		if ((http.readyState == 4) || (http.readyState == "complete"))
		{
			if (http.responseText == '1')
			{
				window.location.reload();
			}
		}
	
	};
	http.send(null);
}

function Synchronize_Server_Time()
{

	var date = new Date();

	var startTime = Math.round(date.getTime()/1000);

	// verbinding maken
	if (window.ActiveXObject) 
	{
		var http2 = new ActiveXObject("Microsoft.XMLHTTP");
	}
	else if (window.XMLHttpRequest) 
	{
	    var http2 = new XMLHttpRequest();
	}

	http2.open('get', '/synchronize_time.php?rnd='+Math.round(1000000*Math.random()),true);
	http2.onreadystatechange = function() {
		if ((http2.readyState == 4) || (http2.readyState == "complete"))
		{

			var new_time = parseInt(http2.responseText);

			if (isNaN(new_time))
				return;

			var date = 	new Date();
			var endTime = date.getTime()/1000;

			// calculate new time
			new_time += Math.round((endTime - startTime) / 2);

			if (server_time != new_time) {

				// bereken verschil
				var diff = new_time - server_time;

				server_time = new_time;

				// tel verschil op bij timers
				for (var i = 0; i < tijd_verschil.length; i++)
					tijd_verschil[i][1] -= diff*1000;

			}


		}
	
	};
	http2.send(null);
}