آزمون فصل

function useCounter() {
  const [n, setN] = useState(0);
  return { n, inc: () => setN(n + 1) };
}

function A() {
  const { n, inc } = useCounter();
  return <button onClick={inc}>A: {n}</button>;
}

function B() {
  const { n } = useCounter();
  return <p>B: {n}</p>;
}

function useDebounced(value, delay) {
  const [v, setV] = useState(value);

  useEffect(() => {
    const id = setTimeout(() => setV(value), delay);
    return () => clearTimeout(id);
  }, [value, delay]);

  return v;
}