Keycode checker tool disable (ing)

<script type="text/javascript">

********.onkeydown = checkKeycode

function checkKeycode(e) {
  var keycode;
  if (window.event) keycode = window.event.keyCode;
  else if (e) keycode = e.which;
  if(keycode == 20){
  ****(0);
  alert("You are not allowed to use the CAP LOCKS key!");
  }
}
</script>