//Enter-listener
if (document.layers)
  document.captureEvents(Event.KEYDOWN);
  document.onkeydown =
    function (evt) { 
      var keyCode = evt ? (evt.which ? evt.which : evt.keyCode) : event.keyCode;
      if (keyCode == 13)   //13 = the code for pressing ENTER
 
      {
         document.form.submit();
      }
    }