👀 Views: 47 💬 Answers: 1 📅 Created: 2025-06-13

react hooks useEffect JavaScript

I'm relatively new to this, so bear with me... Quick question that's been bugging me - This might be a silly question, but I'm working with an scenario with a custom React hook that utilizes `useEffect`. I created this hook to manage a countdown timer based on a prop called `initialCount`. The question is that when I update the `initialCount` prop, the `useEffect` that is supposed to reset the timer does not re-trigger as expected. I'm using React 18 and here's a simplified version of my code: ```javascript import { useEffect, useState } from 'react'; const useCountdown = (initialCount) => { const [count, setCount] = useState(initialCount); useEffect(() => { setCount(initialCount); }, [initialCount]); useEffect(() => { if (count > 0) { const timer = setInterval(() => { setCount((prevCount) => prevCount - 1); }, 1000); return () => clearInterval(timer); } }, [count]); return count; }; const CountdownComponent = ({ initialCount }) => { const count = useCountdown(initialCount); return <div>{count}</div>; }; ``` When I render `CountdownComponent` with a new `initialCount`, the countdown doesn't restart as expected. I tried adding console logs and I can see that the first `useEffect` runs correctly, but the second one doesn't trigger afterwards. The countdown continues from the previous count instead of resetting. I've also verified that the prop actually changes by checking the parent component's state. Is there something I’m missing in the dependency array of my `useEffect`, or is there a better way to handle the countdown reset when the prop changes? The expected behavior is that the countdown should start over whenever `initialCount` is updated. This is part of a larger application I'm building. What's the best practice here? For context: I'm using Javascript on Windows. This issue appeared after updating to Javascript stable. I appreciate any insights!