title: Is it necessary to wait for window load event before initialising a ReactJS app?
body: <p>Is there any reason to wait for a window load event before initialising a react app?</p>
  
  <pre><code>window.addEventListener('load', () =&gt; {
     ReactDOM.render(
       &lt;h1&gt;Reactastic!&lt;/h1&gt;,
       document.getElementById('rootElement')
     );
  }, false);
  </code></pre>
  
  <p>As long as <code>rootElement</code> is defined in html, not hidden or created dynamically by javascript, is there any possibility that it won't be available in time for React to init?</p>
  
  <p>Edit: This is also assuming that the javascript is loaded in the footer.</p>