title: dropdown menu in my chrome extension
body: <p>I buil an google-chrome-extension and now want to add a dropdown menu.
  My problem is that when I click on of my menu-points its open a new chrome tab with my popup.html and don't reload it.
  I tried this and the way with <code>&lt;ul&gt;</code> and <code>&lt;li&gt;</code>.</p>
  
  <pre><code>&lt;div class="dropdown"&gt;
          &lt;button class="dropbtn"&gt;Dropdown&lt;/button&gt;
          &lt;div class="dropdown-content"&gt;
              &lt;a id="menu1" href="#"&gt;menu1&lt;/a&gt;
              &lt;a id="menu2" href="#"&gt;menu2&lt;/a&gt;
              &lt;a id="menu3" href="#"&gt;menu3&lt;/a&gt;
          &lt;/div&gt;
   &lt;/div&gt;
  </code></pre>
  
  <p>I want to use it to run some JavaScript after select.</p>