title: Javascript: How to add class to element without ID and Class?
body: <p>I am newby... :)</p>
  <p>I have this code:</p>
  <pre><code>&lt;div class=&quot;menu&quot;&gt;
    &lt;ul&gt;
      &lt;li&gt;&lt;/li&gt;
      ...
    &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  <p>I need to add class &quot;nav&quot; to <code>&lt;ul&gt;</code>
  element to make it like this one: <code>&lt;ul class=&quot;nav&quot;&gt;</code></p>
  <p>Can you help me? Cuz idk how to use &quot;<strong>GetElementByClass</strong>&quot; right now?</p>