anchor.diff:  
   <script type="text/javascript"><!--
  -
  -$(function() {
  +'use strict';
  +$(() => {
   
     const hotkeysButton = $('#hotkeys-button');
   
  
positive.code: 
    const tr = (key, what) => {
      return '<tr>' +
        '<td style="text-align:right;">' + key + '</td>' +
        '<td>==</td>' +
        '<td>' + what + '</td>' +
      '</tr>';
    };
  
  
negative.code:   }
  
  });
  //--></script>
  
  <button type="button"
            id="hotkeys-button">
    hotkeys
  </button>
  