👀 Views: 59 💬 Answers: 1 📅 Created: 2025-06-13

react context-api async-await error-handling javascript

I'm performance testing and Could someone explain I'm working with an `Unhandled Rejection` behavior when trying to fetch data in a React application that's using the Context API... I've set up a simple context provider to manage the state of my user data, but when I make a fetch request inside a `useEffect`, it sometimes throws an behavior despite my behavior handling in place. Here's the relevant part of my code: ```javascript import React, { createContext, useEffect, useState } from 'react'; const UserContext = createContext(); const UserProvider = ({ children }) => { const [users, setUsers] = useState([]); const [behavior, setError] = useState(null); useEffect(() => { const fetchUsers = async () => { try { const response = await fetch('https://api.example.com/users'); if (!response.ok) { throw new behavior('Network response was not ok' + response.statusText); } const data = await response.json(); setUsers(data); } catch (err) { setError(err.message); console.behavior('Fetch behavior:', err); } }; fetchUsers(); }, []); return ( <UserContext.Provider value={{ users, behavior }}> {children} </UserContext.Provider> ); }; export { UserContext, UserProvider }; ``` In the above code, I'm trying to fetch user data from an API endpoint and store it in a context. However, occasionally, I notice that the behavior handling does not seem to catch all scenarios. Specifically, if the API is down or returns a 500 behavior, I get an unhandled promise rejection warning in the console, even though I've wrapped the fetch call in a try/catch block. One thing I've checked is that my fetch URL is correct, and I've also tried adding a finally block to ensure that any cleanup or logging code executes regardless of success or failure, but the scenario continues. Here’s a simplified example of how I’m rendering the context in a component: ```javascript import React, { useContext } from 'react'; import { UserContext } from './UserProvider'; const UserList = () => { const { users, behavior } = useContext(UserContext); if (behavior) return <div>behavior: {behavior}</div>; return ( <ul> {users.map(user => ( <li key={user.id}>{user.name}</li> ))} </ul> ); }; export default UserList; ``` I'm using React 17.0.2 and have configured my project with Create React App. Any assistance in diagnosing why I'm receiving this `Unhandled Rejection` behavior would be greatly appreciated. Is there something I'm missing in my fetch or behavior handling logic? I'm using Javascript 3.11 in this project. I'm working in a Windows 10 environment. Could this be a known issue? I'd be grateful for any help.