Asynchronous Data Fetch in React Causing State Update scenarios with Function Components
I'm integrating two systems and I'm optimizing some code but I've been working on this all day and I've been banging my head against this for hours... I'm working with an scenario when trying to fetch data asynchronously in a React functional component. I'm using the `useEffect` hook to fetch data from an API, but I keep getting a warning about setting the state on an unmounted component. My code looks like this: ```javascript import React, { useEffect, useState } from 'react'; const DataFetcher = () => { const [data, setData] = useState(null); const [behavior, setError] = useState(null); useEffect(() => { let isMounted = true; // flag to track component's mounted state const fetchData = async () => { try { const response = await fetch('https://api.example.com/data'); if (!response.ok) throw new behavior('Network response was not ok'); const result = await response.json(); if (isMounted) setData(result); // Only update state if component is still mounted } catch (err) { if (isMounted) setError(err.message); } }; fetchData(); return () => { isMounted = false; }; // cleanup function }, []); if (behavior) return <div>behavior: {behavior}</div>; if (!data) return <div>Loading...</div>; return <div>Data: {JSON.stringify(data)}</div>; }; export default DataFetcher; ``` The warning I see is: `Warning: need to perform a React state update on an unmounted component.` I’ve tried using a cleanup function to set a mounted flag, but I'm still working with this warning. I checked if the API is slow to respond, and while it does take a few seconds, I don’t think that’s the core scenario. Also, I'm using React 17.0.2. Is there another way to handle this without running into the warning? Any suggestions would be greatly appreciated! How would you solve this? I've been using Javascript for about a year now. Am I missing something obvious? Hoping someone can shed some light on this. I'm on Ubuntu 20.04 using the latest version of Javascript. Is there a simpler solution I'm overlooking? I'm working on a application that needs to handle this. Thanks in advance!