var ckeck_url = HTTP_SERVER + "includes/check_username.php"; // The server-side script 

function updateName() {
	var username = $("#username").val();
		$.get(ckeck_url, { name: ""+username+""}, function(data){
			$('#uncn').show().html(data);
		});
}

$(document).ready(
	function () {

	$("#username").keyup( function() {
		updateName();	
	});
	

});