var xmlHttp
	
	function checkUserScreenNameDuplicate(id,name)
	{ 		 
			var url="./../check_userscreenname_duplicate.php?id="+ id +"&name=" + name;	
		 xmlHttp=GetXmlHttpObject(responseDuplicateScreenName)
			xmlHttp.open("GET", url , true)
			xmlHttp.send(null)
	} 
	
	
	
	function responseDuplicateScreenName() 
	{  	 	 	 	 	 
			if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
			{ 	  
			 		if(xmlHttp.responseText == 1)
	  			{  
	  				 alert('Screen Name Already Exists '); 
	  				 document.signupForm.screen_name.focus();				
	  				  										
	  			}
	  			else if(xmlHttp.responseText == 0)
	  			{
	  			  document.signupForm.submit();
	  			}
				
			} 
	} 
	
	
	
	
	function GetXmlHttpObject(handler)
	{ 
		var objXmlHttp=null
	
		if (navigator.userAgent.indexOf("Opera")>=0)
		{
			alert("This example doesn't work in Opera") 
			return 
		}
		if (navigator.userAgent.indexOf("MSIE")>=0)
		{ 
			var strName="Msxml2.XMLHTTP"
			if (navigator.appVersion.indexOf("MSIE 5.5")>=0)
			{
				strName="Microsoft.XMLHTTP"
			} 
			try
			{ 
				objXmlHttp=new ActiveXObject(strName)
				objXmlHttp.onreadystatechange=handler 
				return objXmlHttp
			} 
			catch(e)
			{ 
				alert("Error. Scripting for ActiveX might be disabled") 
				return 
			} 
		} 
			if (navigator.userAgent.indexOf("Mozilla")>=0)
			{
				objXmlHttp=new XMLHttpRequest()
				objXmlHttp.onload=handler
				objXmlHttp.onerror=handler 
				return objXmlHttp
			}
	}