👀 Views: 3 💬 Answers: 1 📅 Created: 2025-06-04

reactjs usecontext usecallback JavaScript

I'm relatively new to this, so bear with me... Could someone explain I've been banging my head against this for hours. I'm facing an issue where a child component that consumes a context via `useContext` is not receiving the latest values from the context when a state update occurs in the provider. I'm using React 18 and have implemented the context provider with a state managed by `useReducer`. Here's a simplified version of my code: ```javascript // Context.js import React, { createContext, useReducer } from 'react'; const initialState = { user: null }; const UserContext = createContext(); const reducer = (state, action) => { switch (action.type) { case 'SET_USER': return { ...state, user: action.payload }; default: return state; } }; export const UserProvider = ({ children }) => { const [state, dispatch] = useReducer(reducer, initialState); return ( <UserContext.Provider value={{ state, dispatch }}> {children} </UserContext.Provider> ); }; export const useUserContext = () => React.useContext(UserContext); ``` ```javascript // ChildComponent.js import React, { useCallback } from 'react'; import { useUserContext } from './Context'; const ChildComponent = () => { const { state, dispatch } = useUserContext(); const handleClick = useCallback(() => { dispatch({ type: 'SET_USER', payload: { name: 'John Doe' } }); }, [dispatch]); return ( <div> <h1>User: {state.user ? state.user.name : 'No user'}</h1> <button onClick={handleClick}>Set User</button> </div> ); }; export default ChildComponent; ``` The issue arises when I click the button to set the user. Sometimes, the user name doesn't update, and I see the old value (or `No user`) displayed instead of the expected name. I've verified that the `dispatch` function is being called correctly, but it seems like the child component does not re-render with the new state. I've tried moving the `dispatch` call directly into the component without `useCallback`, but that didn’t make a difference. Additionally, I checked for memoization in parent components that might be affecting the re-render, but nothing seems to be causing the stale closure issue. Is there a workaround or best practice to ensure that the `ChildComponent` always has access to the latest context values? Any insights would be greatly appreciated. My development environment is Ubuntu. This issue appeared after updating to Javascript 3.11. The stack includes Javascript and several other technologies. This is happening in both development and production on Windows 11.