title: Move div content into another div using pure javascript
body: <p>I have this HTML setup:</p>
  
  <pre><code>&lt;div class="one"&gt;
      &lt;div class="text"&gt;One&lt;/div&gt;
      &lt;div class="text"&gt;One&lt;/div&gt;
  &lt;/div&gt;
  
  &lt;div class="two"&gt;
      &lt;div class="text"&gt;Two&lt;/div&gt;
      &lt;div class="text"&gt;Two&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I want to move the content of div <code>.two</code> into <code>.one</code> using pure javascript (not jQuery) so we get:</p>
  
  <pre><code>&lt;div class="one"&gt;
      &lt;div class="text"&gt;One&lt;/div&gt;
      &lt;div class="text"&gt;One&lt;/div&gt;
      &lt;div class="text"&gt;Two&lt;/div&gt;
      &lt;div class="text"&gt;Two&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>What is the best way to do this with <em>millisecond</em> performance in mind?</p>