title: Which key does the e.metaKey refer to in JavaScript MouseEvent?
body: <p><code>MouseEvent.metaKey</code> doesn't seem to work. On both FireFox and Chrome, it returns <code>false</code> even if I hold the <kbd>Win</kbd> key while clicking:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!doctype html&gt;
  &lt;button onclick=alert(event.metaKey)&gt;click while holding "meta key"&lt;/button&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>MDN <a href="https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/metaKey" rel="noreferrer">states</a>:</p>
  
  <blockquote>
    <p>The <code>MouseEvent.metaKey</code> read-only property returning a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean" rel="noreferrer"><em><code>Boolean</code></em></a> that
    indicates if the <kbd>Meta</kbd> key was pressed (<em><code>true</code></em>) or not (<em><code>false</code></em>) when the
    event occured.</p>
    
    <p>Note: On Macintosh keyboards, this is the command key (<kbd>⌘</kbd>). On Windows
    keyboards, this is the windows key (<kbd>⊞</kbd>).</p>
    
    <h3>Browser Compatibility</h3>
    
    <p><img src="https://i.stack.imgur.com/tnNTO.png" alt="enter image description here"></p>
  </blockquote>
  
  <p>MDN claims <code>MouseEvent.metaKey</code> is supported on FireFox and Chrome, but it's not working.</p>
  
  <p>Which key does  <code>MouseEvent.metaKey</code>  refer to?</p>
  
  <p>Why is the above code not working?</p>