useEffect

Define a cleanup function inside the useEffect return statement
To handle cleanup for a subscription in useEffect, you should define a cleanup function inside the return statement of the useEffect callback. React will automatically call this cleanup function when the component unmounts or before re-running the effect.
Use the return statement to call the cleanup function
Manually unsubscribe in the component's componentWillUnmount
There's no need to handle cleanup for subscriptions in useEffect

Question 21 of 22 in useEffect