title: React, display content of root node while loading
body: <p>Let's say I have following template:</p>
  
  <pre><code>...
  &lt;body&gt;
    &lt;div id="root"&gt;Loading...&lt;/div&gt;
  &lt;/body&gt;
  ...
  </code></pre>
  
  <p>and React component is something very obvious like</p>
  
  <pre><code>ReactDOM.render(RootContainer, document.getElementById('root'));
  </code></pre>
  
  <p>(Examples are simplified as much as possible)</p>
  
  <p>What I want is to show contents of the div while React is processing request and to replace "Loading..." with actual app once it is loaded.</p>
  
  <p>How should I do that? I see a way of adding another div with "loading" message and hiding it once app is loaded but it seems to me like a dirty way</p>