React: Unexpected Re-renders in a Complex Form with useMemo and useCallback
I'm optimizing some code but I'm building a feature where I have a complex form built with React (version 17.0.2) that uses `useMemo` and `useCallback` to optimize performance, but I'm experiencing unexpected re-renders of certain components... The form allows users to add multiple entries dynamically, and I’m trying to optimize it because the number of entries can grow quite large. However, I noticed that even though I expected certain inputs to be memoized, they still trigger re-renders whenever I update other form fields. Here’s a simplified version of my code: ```javascript import React, { useState, useCallback, useMemo } from 'react'; const MyForm = () => { const [entries, setEntries] = useState([{ id: 1, value: '' }]); const handleChange = (id, newValue) => { setEntries(prevEntries => prevEntries.map(entry => entry.id === id ? { ...entry, value: newValue } : entry ) ); }; const handleAddEntry = () => { const newEntry = { id: entries.length + 1, value: '' }; setEntries([...entries, newEntry]); }; const renderEntries = useMemo(() => { return entries.map(entry => ( <EntryField key={entry.id} id={entry.id} value={entry.value} onChange={handleChange} /> )); }, [entries]); return ( <div> {renderEntries} <button onClick={handleAddEntry}>Add Entry</button> </div> ); }; const EntryField = React.memo(({ id, value, onChange }) => { console.log(`Rendering EntryField ${id}`); return ( <input type="text" value={value} onChange={e => onChange(id, e.target.value)} /> ); }); export default MyForm; ``` I’m utilizing `React.memo` for the `EntryField` component to prevent unnecessary re-renders, but I’m still seeing log messages indicating it’s re-rendering when other state changes occur. When I change one field, all the `EntryField` components seem to be affected. I’ve checked to ensure that the `onChange` handler is stable (it is created outside of the render), yet I suspect that the way I’m updating the entries is causing the memoization to fail. Are there best practices for handling this scenario, or could I be missing something in my `useMemo` usage? Any insights or suggestions would be greatly appreciated! My team is using Javascript for this microservice. Am I missing something obvious? This is part of a larger application I'm building. Any help would be greatly appreciated!