title: Check if elements (DOM Nodes) are siblings
body: <p>How to check if two DOM elements are siblings?</p>
  <h3>Example DOM structure:</h3>
  <pre><code>&lt;div&gt;
      &lt;a&gt;&lt;/a&gt;
      &lt;b&gt;&lt;/b&gt;
      &lt;p&gt;&lt;/p&gt;
  &lt;/div&gt;
  &lt;i&gt;&lt;/i&gt;
  </code></pre>
  <p>Test if <code>&lt;b&gt;</code> is a sibling of <code>&lt;a&gt;</code> but not of <code>&lt;i&gt;</code></p>