ff ctr+s problem

HTML

<textarea id="mytextarea">

</textarea>

JavaScript

$("#mytextarea").on("keypress keydown", function(e) {
  if ((e.which == '115' || e.which == '83') && (e.ctrlKey || e.metaKey)) {
    e.preventDefault();
    alert("Ctrl-s pressed");
    return false;
  }
  return true;
});