[ PROMPT_NODE_25177 ]
Advanced Use Latest
[ SKILL_DOCUMENTATION ]
## useLatest for Stable Callback Refs
Access latest values in callbacks without adding them to dependency arrays. Prevents effect re-runs while avoiding stale closures.
**Implementation:**
```typescript
function useLatest(value: T) {
const ref = useRef(value)
useEffect(() => {
ref.current = value
}, [value])
return ref
}
```
**Incorrect (effect re-runs on every callback change):**
```tsx
function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
const [query, setQuery] = useState('')
useEffect(() => {
const timeout = setTimeout(() => onSearch(query), 300)
return () => clearTimeout(timeout)
}, [query, onSearch])
}
```
**Correct (stable effect, fresh callback):**
```tsx
function SearchInput({ onSearch }: { onSearch: (q: string) => void }) {
const [query, setQuery] = useState('')
const onSearchRef = useLatest(onSearch)
useEffect(() => {
const timeout = setTimeout(() => onSearchRef.current(query), 300)
return () => clearTimeout(timeout)
}, [query])
}
```