React Hook: useInterval for Repeating Actions

import { useEffect, useRef } from 'react';

const useInterval = (callback, delay) => {
  const savedCallback = useRef();

  useEffect(() => {
    savedCallback.current = callback;
  }, [callback]);

  useEffect(() => {
    const tick = () => {
      savedCallback.current();
    };
    if (delay !== null) {
      let id = setInterval(tick, delay);
      return () => clearInterval(id);
    }
  }, [delay]);
};

export default useInterval;

How it works: The `useInterval` hook allows you to run a function `callback` every `delay` milliseconds. It uses `useRef` to store the latest `callback` function, preventing stale closures. The `useEffect` hook then sets up and tears down the `setInterval`, ensuring it's cleaned up when the component unmounts or the `delay` changes. This is invaluable for features requiring periodic updates, like countdown timers or data polling.