👀 Views: 95 💬 Answers: 1 📅 Created: 2025-07-22

reactjs usecallback useeffect javascript

I'm reviewing some code and I'm relatively new to this, so bear with me. I'm working with a question in my React 18 application where a nested component doesn't seem to reflect the latest state changes when using `useCallback` with `useEffect`. I have a parent component that maintains a state for a list of items and passes a callback to a child component to update an item in that list. Here's a simplified version of my code: ```javascript import React, { useState, useCallback, useEffect } from 'react'; const Parent = () => { const [items, setItems] = useState(['item1', 'item2', 'item3']); const updateItem = useCallback((index, newValue) => { setItems(prevItems => { const updatedItems = [...prevItems]; updatedItems[index] = newValue; return updatedItems; }); }, []); return <Child items={items} onUpdateItem={updateItem} />; }; const Child = React.memo(({ items, onUpdateItem }) => { useEffect(() => { console.log('Child component items:', items); }, [items]); const handleChange = (index) => { onUpdateItem(index, `updatedItem${index}`); }; return ( <div> {items.map((item, index) => ( <div key={index} onClick={() => handleChange(index)}>{item}</div> ))} </div> ); }); export default Parent; ``` The question is that when I click on an item in the `Child` component to update it, the `Child` component logs the old state instead of the updated one. I thought using `useCallback` would ensure that the latest item state is passed down, but it seems like the stale closure is causing the scenario. I've tried both adding `items` to the dependency array of `useCallback` and using the functional update in `setItems`, but those don't seem to fix the question. I'm getting no behavior messages, and the UI updates correctly after a second click, but I need the `Child` to reflect the changes immediately. Is there something I'm missing or a better pattern I should be using in this scenario? My development environment is macOS. Has anyone else encountered this? I'm working in a Windows 11 environment. Is there a simpler solution I'm overlooking?