var xmlHttp
	
	function GetUnameXmlHttpObject(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)
		{    
			document.getElementById("check_username_result").innerHTML = '<table><tr><td><img src="indicator.gif" width="16" height="16"></td><td>Loading...</td></tr></table>' 
			objXmlHttp = new XMLHttpRequest()
			objXmlHttp.onload  = handler
			objXmlHttp.onerror = handler 
			return objXmlHttp
		}  
		
	}  /*-- FUNCTION GetUnameXmlHttpObject() ENDS HERE --*/
  
	 function checkUsernameExist() {
		 var user_name = document.user_add_frm.username.value;  
		 var hidden_user_name = document.user_add_frm.hidden_user_name.value;
		 if(user_name != '') {		
			 if(IsBlank('user_add_frm','username')) {
				    alert("Username Field is Empty");
				    document.user_add_frm.username.focus();
			 }
			 if(user_name != hidden_user_name) {
			 		var url = "check_exists.php?act=user_name&user_name="+user_name
				    xmlHttp = GetUnameXmlHttpObject(checkUsernameExistResult)
				    xmlHttp.open("GET",url, true)
				    xmlHttp.send(null)
			 }
		 }
		 
	 } /*-- FUNCTION checkEmailExist() ENDS HERE --*/
  
	function checkUsernameExistResult() 
	{   
		if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")  
		{    
			  if(trimString(xmlHttp.responseText) == "<font color='#ff0000;'>&nbsp;Username is already Exists</font>")
			  {	  
			  	  document.user_add_frm.user_exist_validate.value = "exist";
			  	  document.getElementById("check_username_result").innerHTML = "<font color='#ff0000;'>&nbsp;This username is already in use, please choose a different one</font>";
			  }
			  else
			  {
			  	  document.user_add_frm.user_exist_validate.value = "not_exist";
			  	  document.getElementById("check_username_result").innerHTML = "";
			  }			  
		}
		else {
			 document.getElementById("check_username_result").innerHTML = '<table><tr><td><img src="indicator.gif" width="16" height="16"></td><td>Loading...</td></tr></table>';
		} 
		
	}  /*-- FUNCTION checkEmailExistResult() ENDS HERE --*/