React 18: Unexpected Behavior When Using Multiple useReducer Hooks in Nested Components
I need some guidance on I tried several approaches but none seem to work. I'm experiencing unexpected behavior when utilizing multiple `useReducer` hooks in nested components in my React 18 application. I have a parent component that manages its own state using a reducer and passes down state and dispatch functions to child components. The issue arises when the child components update their local state, which seems to cause the parent component to re-render unexpectedly, even though I thought the child components should be isolated. Here's a simplified version of my code: ```javascript import React, { useReducer } from 'react'; const parentReducer = (state, action) => { switch (action.type) { case 'UPDATE_PARENT': return { ...state, parentValue: action.payload }; default: return state; } }; const childReducer = (state, action) => { switch (action.type) { case 'UPDATE_CHILD': return { ...state, childValue: action.payload }; default: return state; } }; const ParentComponent = () => { const [parentState, parentDispatch] = useReducer(parentReducer, { parentValue: '' }); return ( <div> <h1>Parent Value: {parentState.parentValue}</h1> <ChildComponent parentDispatch={parentDispatch} /> </div> ); }; const ChildComponent = ({ parentDispatch }) => { const [childState, childDispatch] = useReducer(childReducer, { childValue: '' }); const handleChange = (e) => { childDispatch({ type: 'UPDATE_CHILD', payload: e.target.value }); parentDispatch({ type: 'UPDATE_PARENT', payload: e.target.value }); }; return ( <div> <input type="text" value={childState.childValue} onChange={handleChange} /> <p>Child Value: {childState.childValue}</p> </div> ); }; export default ParentComponent; ``` Here, when I type in the input field within `ChildComponent`, I expect to only update the child state, but I notice that the `ParentComponent` also re-renders, which leads to `Parent Value` being updated as well (as it mirrors the child input). I would think that since `childDispatch` is local to the `ChildComponent`, it shouldn't affect the parent state this way. I've tried moving the `parentDispatch` out of the `handleChange` function, but that didn't resolve the issue. Additionally, I’ve considered the idea that this could be due to the way React batches updates, but I can't pinpoint what's causing the parent to re-render when I'm only updating the child's state. How can I isolate the state updates in a way that prevents the parent component from re-rendering unnecessarily while still allowing the communication between parent and child components? Also, any insights on best practices for using multiple `useReducer` hooks in nested components would be greatly appreciated! My development environment is macOS. What's the best practice here? I'm working with Javascript in a Docker container on CentOS. Has anyone else encountered this? I'm working in a Ubuntu 20.04 environment. Any advice would be much appreciated.