title: How to get innerHTML of ReactDOM mounted element
body: <p>HTML markup like this:</p>
  
  <pre><code>&lt;div id="my-component"&gt;
      &lt;div&gt;Some content goes here&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Having this in <code>app.js</code> file:</p>
  
  <pre><code>ReactDOM.render(&lt;MyComponent/&gt;, document.getElementById('my-component));
  </code></pre>
  
  <p>I want to get innetHTML of <code>#my-component</code> before that react component is mounted.</p>
  
  <p>Using <code>ReactDOM.findDOMNode</code> in <code>componentWillMount</code> is not working because the element is not still mounted so returns null and in <code>componentDidMount</code> innerHTML has been replaced.</p>