title: Disable ALT+F4, yes I know it isn't recommended
body: <p>I need a JavaScript script that would disable users from closing using ALT+F4. I have looked everywhere but it just everyone just says it isn't advised. </p>
  
  <p>May not even be possible, if it isn't I will just have to detect when the user does quit out this way and log it in a database. </p>
  
  <p>Here is my current script, it detects if the user presses either ALT or F4, but I can't get it to cancel that key press. Is there a way to make the browser think the user pressed another key as well so the combo would be ALT + G + F4 for example, which would disrupt the ALT+F4 combo? </p>
  
  <pre><code>//Run on keydown, disable user from quiting via ALT+F4
  document.onkeydown = function(evt) {
      evt = evt || window.event;
      //Get key unicode
      var unicode = evt.keyCode ? evt.keyCode : evt.charCode;
  
      //Check it it's ALT or F4 (115)
      if (unicode == 115 || evt.altKey == 1)
      {
          window.event.cancelBubble = true;
          window.event.returnValue = false;
      }
  };
  </code></pre>