React functional components vs classical components : <p>I'm trying to understand when to use React functional components vs. classes and reading from the <a href="https://facebook.github.io/react/blog/2015/12/18/react-components-elements-and-instances.html" rel="noreferrer">docs</a> they don't really go into detail. Can you give me some primary examples of the below of when you would want a specific feature of a class to make a component?</p>

<blockquote>
  <p>A functional component is less powerful but is simpler, and acts like
  a class component with just a single render() method. Unless you need
  features available only in a class, we encourage you to use functional
  components instead.</p>
</blockquote>
