var xmlHttpUser

function stateChangedUser() 
{ 
if (xmlHttpUser.readyState==4)
{
	if(xmlHttpUser.responseText==''){
		document.getElementById("usererror").innerHTML=xmlHttpUser.responseText;			
	}
	
	if(document.getElementById("usererror").innerHTML==''){
		document.getElementById("Submit").disabled=false;
	}
	
	if(xmlHttpUser.responseText=='Username taken. Choose another one')
	{	
		document.getElementById("usererror").innerHTML=xmlHttpUser.responseText;
		document.getElementById("Submit").disabled=true;
	}
}
}

function GetxmlHttpUserObject()
{
var xmlHttpUser=null;
try
  {
  // Firefox, Opera 8.0+, Safari
  xmlHttpUser=new xmlHttpRequest();
  }
catch (e)
  {
  // Internet Explorer
  try
    {
    xmlHttpUser=new ActiveXObject("Msxml2.XMLHTTP");
    }
  catch (e)
    {
    xmlHttpUser=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
return xmlHttpUser;
}

function checkuser(str)
{
	if (str.length==0)
	{ 
		document.getElementById("usererror").innerHTML="";
		return;
	}
	xmlHttpUser=GetXmlHttpObject()
	if (xmlHttpUser==null)
	{
		alert ("Your browser does not support AJAX!");
		return;
	} 
	var url="valemail.php";
	url=url+"?q="+str;
	url=url+"&sid="+Math.random();
	url=url+"&action=user"
	xmlHttpUser.onreadystatechange=stateChangedUser;
	xmlHttpUser.open("GET",url,true);
	xmlHttpUser.send(null);
}