title: keydown event no longer returns key/code/keyCode etc. for password fields in Firefox
body: <p>I used to be able to access <code>event.key</code> and/or <code>event.code</code> and/or <code>event.keyCode</code> and/or jQuery's standardised <code>event.which</code> for <code>keydown</code> events on password and text inputs.</p>
  
  <p>As of writing, this still works in Chrome (71) but has stopped working in Firefox (65).</p>
  
  <p>See fiddle:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>$('input').on('keydown', e =&gt; {
     $('pre').append("keyCode: " + e.which + " "  + e.key + " "  + e.code + "\n"); });
  $('pre').append('type in box\n');</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.10.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;pre&gt;&lt;/pre&gt;
  &lt;input type="password" &gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>On Chrome this outputs expected values, e.g. </p>
  
  <pre><code>keyCode: 68 d
  keyCode: 83 s
  keyCode: 18 Alt
  </code></pre>
  
  <p>On firefox this now outputs (regardless which keys are pressed):</p>
  
  <pre><code>keyCode: 229 Process undefined
  keyCode: 229 Process undefined
  keyCode: 229 Process undefined
  </code></pre>
  
  <p>Firefox does not behave this way if you change the input to <code>text</code>.</p>
  
  <p><a href="https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/code" rel="nofollow noreferrer">MDN</a> does not seem to make reference to this.</p>
  
  <p>I've changed some of my code to use <code>keypress</code> for now, which seems to work still, but I'd like to understand why and if there's a way to do it with keydown/up.</p>