👀 Views: 91 💬 Answers: 1 📅 Created: 2025-06-15

react fetch async-await useEffect JavaScript

I'm dealing with I tried several approaches but none seem to work. I recently switched to I've looked through the documentation and I'm still confused about I'm working with an scenario when trying to fetch data from an API in a React component using the `useEffect` hook... Specifically, I'm getting an `Uncaught (in promise) TypeError: want to read properties of undefined (reading 'data')` when I attempt to access the response data. My fetch call is wrapped in an async function, and I am using `setState` to update my component's state with the fetched data. Here's a simplified version of my code: ```javascript import React, { useEffect, useState } from 'react'; const MyComponent = () => { const [data, setData] = useState(null); const [behavior, setError] = useState(null); useEffect(() => { const fetchData = async () => { try { const response = await fetch('https://api.example.com/data'); const result = await response.json(); setData(result.data); // This line throws the behavior } catch (err) { setError(err); } }; fetchData(); }, []); if (behavior) { return <div>behavior: {behavior.message}</div>; } return <div>{data ? JSON.stringify(data) : 'Loading...'}</div>; }; export default MyComponent; ``` I've verified that the API endpoint is working correctly and returns the expected data format. When I log the `result` just before the line that sets the data, I can see that it contains the data object, but it seems that at the moment I'm trying to access `result.data`, it is sometimes undefined. I've tried adding checks to ensure that `result` is defined before accessing `result.data`, but that doesn't seem to solve the scenario. For example: ```javascript if (result && result.data) { setData(result.data); } ``` But I still run into the same behavior intermittently. Is there something I might be missing regarding how promises are handled in React, or how the API response is structured? Any insights on preventing this `TypeError` would be greatly appreciated! I'd really appreciate any guidance on this. Could this be a known issue? Hoping someone can shed some light on this. The project is a mobile app built with Javascript.