Handling Multiple Promises with React useEffect Without Race Conditions
I've looked through the documentation and I'm still confused about Quick question that's been bugging me - I'm facing a challenge with my React component where I use `useEffect` to fetch data from multiple APIs simultaneously. The problem arises when I try to handle the responses. If one promise resolves after another, the state updates can become inconsistent, leading to unexpected behaviors in my UI. I'm using React 17 and trying to ensure that the data for each promise is set correctly without overwriting the state from another promise. Here's a simplified version of my code: ```javascript import React, { useEffect, useState } from 'react'; const MyComponent = () => { const [data, setData] = useState({}); const [loading, setLoading] = useState(true); useEffect(() => { setLoading(true); const fetchData1 = fetch('https://api.example.com/data1'); const fetchData2 = fetch('https://api.example.com/data2'); Promise.all([fetchData1, fetchData2]) .then(async (responses) => { const data1 = await responses[0].json(); const data2 = await responses[1].json(); setData(prevData => ({ ...prevData, data1, data2 })); }) .catch(error => { console.error('Error fetching data:', error); }) .finally(() => { setLoading(false); }); }, []); if (loading) return <div>Loading...</div>; return ( <div> <h1>Data from API 1</h1> <pre>{JSON.stringify(data.data1, null, 2)}</pre> <h1>Data from API 2</h1> <pre>{JSON.stringify(data.data2, null, 2)}</pre> </div> ); }; export default MyComponent; ``` I'm seeing that sometimes the `setData` call seems to overwrite previous data, resulting in only the last fetched data being displayed. I tried using the functional form of `setData` to preserve the existing state, but it still feels like there's potential for race conditions, especially in more complex scenarios with more APIs. Is there a recommended way to handle this in a way that guarantees the integrity of my state updates? Any insights on how to manage multiple concurrent requests effectively would be greatly appreciated! For context: I'm using Javascript on Linux. Is there a better approach? This is part of a larger web app I'm building. Is there a better approach? Any ideas how to fix this?