title: find a nested div tag
body: <p>I have two div tags like bellow:</p>
  
  <pre><code>&lt;body&gt;
     &lt;div id="divParent"&gt;
        &lt;div id="divChild"&gt;&lt;/div&gt;
     &lt;/div&gt;
  &lt;/body&gt;
  </code></pre>
  
  <p>How can I get the divChild using JavaScript?</p>