title: Is it safe to store state on a component instance in React?
body: <p>Before React 16 it was considered dangerous to store state in a component instance (assigning to this.whatever). The React runtime could recreate instances at any time.</p>
  
  <p>This warning has disappeared from the docs. Does this mean it is safe to use <code>this</code> to store state that should not trigger a re-render?</p>