var my;
function check_user(aa){
if(aa.length==0){
document.getElementById('u_span').innerHTML="";	
return; 
	}	
my=new GetXmlHttpObject2();

if(my==null){
	alert('Ajax Dos\'t Working Your Browser');
	return;
	}
var url;
url='check_user.php?a=' + aa + '&r=' + Math.random();
//alert(url);
my.onreadystatechange=statechange2;
my.open('GET',url,true);
my.send(null);
}
function statechange2(){
	if(my.readyState==4){
		//alert(my.responseText);
		document.getElementById('u_span').innerHTML=my.responseText;
		
		}
	
	}


function GetXmlHttpObject2()
{
var xmlHttp2=null;
try
{
// Firefox, Opera 8.0+, Safari
xmlHttp2=new XMLHttpRequest();
}
catch (e)
{
// Internet Explorer
try
{
xmlHttp2=new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e)
{
xmlHttp2=new ActiveXObject("Microsoft.XMLHTTP");
}
}
return xmlHttp2;
}