👀 Views: 32 💬 Answers: 1 📅 Created: 2025-07-05

reactjs usestate usereducer useeffect javascript

I'm following best practices but I'm a bit lost with I'm working with an scenario when trying to combine `useReducer` for state management with local component state updates in my React 18 application. The question arises when I update the local component state based on values derived from the global state managed by `useReducer`. Here's a simplified version of my component: ```javascript import React, { useReducer, useState, useEffect } from 'react'; const initialState = { count: 0, status: 'idle' }; function reducer(state, action) { switch (action.type) { case 'increment': return { ...state, count: state.count + 1 }; case 'setStatus': return { ...state, status: action.payload }; default: throw new behavior(); } } const MyComponent = () => { const [state, dispatch] = useReducer(reducer, initialState); const [localValue, setLocalValue] = useState(''); useEffect(() => { if (state.count > 5) { dispatch({ type: 'setStatus', payload: 'active' }); setLocalValue('Count is high!'); } else { setLocalValue('Count is low.'); } }, [state.count]); return ( <div> <p>Global count: {state.count}</p> <p>Status: {state.status}</p> <p>Local message: {localValue}</p> <button onClick={() => dispatch({ type: 'increment' })}>Increment</button> </div> ); }; export default MyComponent; ``` The scenario is that even when the global `count` is below 5, the `localValue` seems to sometimes retain its previous state when I expect it to update. For instance, if I increment the count to 5, I see 'Count is low.' first, and then it updates to 'Count is high!' with the next increment. But if I quickly click the increment button, sometimes the message stays on 'Count is low.' instead. I've tried adding a check to ensure that `setLocalValue` only runs when the `count` changes, but I'm still seeing inconsistent behavior. The React version I'm using is 18.0.0. What am I missing here? Is there a better way to handle this interaction between `useReducer` and local state? Any insights would be greatly appreciated! What am I doing wrong? I'm coming from a different tech stack and learning Javascript. What are your experiences with this?