title: Does React perform a deep compare or a shallow compare in render method?
body: <p>React Document says</p>
  
  <blockquote>
    <p>React.PureComponent's shouldComponentUpdate() only shallowly compares
    the objects.</p>
  </blockquote>
  
  <p>Does it mean the Component will do a deep compare unless we make it a PureComponent ?</p>