//checks if an email is already in database
function checkUniqueEmail(evt){
	if(!evt){
		evt = window.event;
	}

	var target = evt.target? evt.target : evt.srcElement;

	hideEmailError(target);
	
	if(target.value.length){
		if(emailCheck(target.value, true)){
			var XMLHTTPConn = new XML_HTTP_Conn();
			
			var vars = "action=checkUniqueEmailExe";
			vars += "&email=" + trim(target.value);
			
			
			//alert(groupName)
			//alert(userName)
			
			   XMLHTTPConn.connect(controllerURL, "POST", vars,
			      function(xh) {
				
			        if(xh.responseText == 'null') {
			           // handler
			           return;
			        }
			         
				      var response = xh.responseText.parseJSON();
				      	//alert("Received response");
						//alert(xh.responseText)
						//check if request has succeeded
						
				      if(!response.unique){
				      	showEmailError(target);
				      	target.focus();
					  }else{
					  	hideEmailError(target);
					  }
					   
				 }
			   );
			
		}else{
			target.focus();
		}
	}else{
		hideEmailError(target);
	}

}



//checks if an user name is already in database
function checkUniqueUserName(evt){
	if(!evt){
		evt = window.event;
	}

	var target = evt.target? evt.target : evt.srcElement;

	hideUserNameError(target);

	if(target.value.length){
		var XMLHTTPConn = new XML_HTTP_Conn();
		
		var vars = "action=checkUniqueUserNameExe";
		vars += "&userName=" + trim(target.value);
		
		
		//alert(groupName)
		//alert(userName)
		
		   XMLHTTPConn.connect(controllerURL, "POST", vars,
		      function(xh) {
			
		        if(xh.responseText == 'null') {
		           // handler
		           return;
		        }
		         
			      var response = xh.responseText.parseJSON();
			      	//alert("Received response");
					//alert(xh.responseText)
					//check if request has succeeded
					
			      if(!response.unique){
			      	showUserNameError(target);
			      	target.focus();
				  }else{
				  	hideUserNameError(target);
				  }
				   
			 }
		   );
			
	}else{
		hideUserNameError(target);
	}

}