Missing useEffect Cleanup: leaky event listeners or intervals

My React component sets up event listeners or timers inside useEffect, but I never remove them. Over time, performance degrades—especially if components remount frequently. How should I fix this?

If you don’t clean up side effects like event listeners or intervals, they persist beyond the component’s lifecycle and prevent garbage collection, risking memory leaks and stale callbacks ([turn0search2]turn0search4). Fix Examples: js Copy code useEffect(() => { const handleScroll = () => { /* ... */ }; window.addEventListener('scroll', handleScroll);

const timeoutId = setTimeout(...), intervalId = setInterval(...);

return () => { window.removeEventListener('scroll', handleScroll); clearTimeout(timeoutId); clearInterval(intervalId); }; }, []); Always return a cleanup function to remove listeners and clear timers.