Missing cleanup in useEffect — leaking timers or subscriptions

I register a window resize listener or interval in useEffect but forget to clean it up. Over time, event handlers pile up or continue after unmounting, causing performance issues.

Without cleanup, effects persist beyond component life and retain stale callbacks and memory, leading to leaks or duplicated behavior ([turn0search11], [turn0search6]). Fix: jsx Copy code useEffect(() => { window.addEventListener('resize', handleResize); const id = setInterval(tick, 1000); return () => { window.removeEventListener('resize', handleResize); clearInterval(id); }; }, []);