<script>
 $(document).ready(function(){

 $('#l_id_codigo').keyup(username_check); });

 function username_check(){

 var l_id_codigo = $('#l_id_codigo').val();


 jQuery.ajax({
 type: 'POST', url: 'check.php', data: 'l_id_codigo='+ l_id_codigo, cache: false, success: function(response){
 if(response == 1){
 $('#l_id_codigo').css('border', '1px #090 solid');
 $('#cross').hide(); $('#tick').fadeIn();
 }else{
 $('#l_id_codigo').css('border', '1px #C33 solid');
 $('#tick').hide(); $('#cross').fadeIn();
 }
 }
 });

 }
</script>