Scroll listener properly cleaned

Code reviewCode quality & reviewSenior–Staff~22 min

Review this React TypeScript scroll hook.

What a strong answer looks like

Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix, specific and kind.

0:00 of about 22 min

Mark a line and say what kind of problem it is.0 findings

1function useScrollDirection() {

2 const [dir, setDir] = useState<'up' | 'down'>('up');

3 const last = useRef(0);

5 useEffect(() => {

6 const onScroll = () => {

7 const y = window.scrollY;

8 setDir(y > last.current ? 'down' : 'up');

9 last.current = y;

10 };

11 window.addEventListener('scroll', onScroll, { passive: true });

12 return () => window.removeEventListener('scroll', onScroll);

13 }, []);

15 return dir;

16}

Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.