What is useEffect cleanup in React?

Can you explain what useEffect cleanup is in React?

Sure! In React, useEffect cleanup is a function that runs when a component unmounts or before the effect runs again. It helps to prevent memory leaks by cleaning up resources like subscriptions or timers.

How do I implement cleanup in a useEffect hook?

You can implement cleanup by returning a function from the useEffect hook. For example:

useEffect(() => {
  const timer = setTimeout(() => {
    console.log('Timer triggered');
  }, 1000);

  return () => clearTimeout(timer); // Cleanup function
}, []);

What happens if I forget to include cleanup?

If you forget to include cleanup, it can lead to memory leaks, especially if your component subscribes to events or sets timers. This can cause performance issues in your application.

Are there any best practices for using useEffect cleanup?

Yes! Always clean up subscriptions, timers, and event listeners. Also, ensure that your cleanup function is defined to avoid potential memory leaks.