How does cleanup work in React's useEffect?

How does cleanup work in React's useEffect?

In React, the cleanup function in useEffect is used to clean up side effects before the component unmounts or before the effect runs again.

Can you give me an example of a cleanup function?

Sure! If you set up a subscription in useEffect, you can return a function that unsubscribes from it as cleanup.

What happens if I forget to include a cleanup function?

If you forget to include a cleanup function, it may lead to memory leaks or unwanted behavior, as the side effects may persist.

Is cleanup necessary for all useEffect hooks?

No, cleanup is only necessary if your effect creates side effects that need to be cleaned up, like subscriptions or timers.