← React Beginner Questions - Set 8 Q77

What is the useEffect hook used for?

React Beginner Questions - Set 8

Example

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useEffect(() => {
  const id = setInterval(() => setTick(t => t + 1), 1000);
  return () => clearInterval(id);   // cleanup on unmount
}, []);

What to notice

• Anything outside React — timers, sockets, DOM APIs — belongs here with a cleanup.