👀 Views: 78 💬 Answers: 1 📅 Created: 2025-06-04

react useeffect hooks javascript

I'm deploying to production and I'm dealing with I'm working on a project and hit a roadblock..... I'm encountering an issue with my React functional component where the `useEffect` hook behaves unexpectedly when updating state. My component fetches user data from an API and updates based on a `userId` prop. However, when I change the `userId`, the `useEffect` doesn't seem to trigger a re-fetch under certain conditions. Here's a simplified version of my code: ```javascript import React, { useEffect, useState } from 'react'; const UserProfile = ({ userId }) => { const [userData, setUserData] = useState(null); useEffect(() => { const fetchUserData = async () => { const response = await fetch(`https://api.example.com/users/${userId}`); const data = await response.json(); setUserData(data); }; fetchUserData(); }, [userId]); return <div>{userData ? userData.name : 'Loading...'}</div>; }; export default UserProfile; ``` In this implementation, I'm relying on `userId` as a dependency for the `useEffect`. However, when I switch between user IDs quickly, I sometimes see stale data being displayed, or I get an incomplete state in the component. Specifically, I noticed that if the API response takes longer than expected, the previous user data remains visible before the new data loads. I also tried adding a cleanup function to cancel ongoing fetch requests, but that didn't seem to solve the issue. Here’s what I attempted: ```javascript useEffect(() => { let isMounted = true; const fetchUserData = async () => { const response = await fetch(`https://api.example.com/users/${userId}`); const data = await response.json(); if (isMounted) { setUserData(data); } }; fetchUserData(); return () => { isMounted = false; }; }, [userId]); ``` Clearly, this approach isn’t effective in addressing the delay in data fetching. I'm using React version 17.0.2 and wondering if there's a better pattern or best practice for handling such scenarios. How can I ensure that my component reflects the latest state without displaying the stale data, especially when the `userId` changes rapidly? Any insights or suggestions would be greatly appreciated! I'm working on a service that needs to handle this. How would you solve this? What's the best practice here? I'm on Windows 10 using the latest version of Javascript. Could this be a known issue? I'm on Windows 11 using the latest version of Javascript. For reference, this is a production application. Any suggestions would be helpful.