var xmlhttp;

function showUser(str)
{

xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }
var url="ajax_test.php";
url=url+"?q="+str;
url=url+"&sid="+Math.random();
xmlhttp.onreadystatechange=stateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}

function stateChanged() {
	if (xmlhttp.readyState==4) {
	//document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
	//alert(xmlhttp.responseText);
		if (xmlhttp.responseText == 0) {
			document.addtile.addbutton.disabled=true;
			document.getElementById('tileadd').disabled=true;
			alert ("this tile is not available");			
		}
	}
}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
  {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  return new XMLHttpRequest();
  }
if (window.ActiveXObject)
  {
  // code for IE6, IE5
  return new ActiveXObject("Microsoft.XMLHTTP");
  }
return null;
}