A neat little feature which comes with version 16.8 of React are hooks.
What are Hooks?
Hooks allow you to add state to functional components, or make side effects work in those. Or even bundle up your own stateful logic into an own hook method, that makes the logic be reusable without having to leak the state all over the place.
I could reproduce the highlights of hooks here, but the React people are explaining it well enough. Just read their overview].