var obj;

if(window.XMLHttpRequest)
{obj = new XMLHttpRequest();}

else if(window.ActiveXObject)
{obj = new ActiveXObject("MSXML2.XMLHTTP");}

function check_user()
{
	document.getElementById('userspan').innerHTML = "<img src='includes/images/loading.gif' width='20'>";
	var user = document.reg_form1.user.value;
	var url = 'register/check_user.php?user='+user;
	if(obj) 
	{	
		obj.open("GET", url);
		
		obj.onreadystatechange = function()
		{
		if (obj.readyState == 4 && obj.status == 200) {
		document.getElementById('userspan').innerHTML = obj.responseText;
		}
		}
		obj.send(null);
	}
}