title: Can I access the value of invalid/custom CSS properties from JavaScript?
body: <p>Assume I have the following CSS:</p>
  
  <pre><code>div {
      -my-foo: 42;
  }
  </code></pre>
  
  <p>Can I later in JavaScript somehow know what the value of the <code>-my-foo</code> CSS property is for a given <code>div</code>?</p>