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Question
A teammate memoized a heavy child with React.memo to stop re-renders, and an AI 'helped' by passing the handler below. The child still re-renders on every parent render. Why, and what's the proper fix?
const Parent = () => { const [n, setN] = useState(0); return ( <> <button onClick={() => setN(n + 1)}>+</button> <HeavyChild onSelect={(id) => doThing(id)} /> </> );};// HeavyChild = React.memo(HeavyChildImpl)What a strong answer looks like
Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it — tests, edge cases, reading critically — and how you’d re-prompt or decompose to get it right.
Learn the concepts
Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.
Run or narrate your approach, then ask the coach.