Files
livedash-node/.opencode/skills/vercel-react-best-practices/rules/advanced-use-latest.md
Kaj Kowalski 5bfd762e55 fix: comprehensive TypeScript/build fixes and modernization
- Update tsconfig to ES2024 target and bundler moduleResolution
- Add dynamic imports for chart.js and recharts (bundle optimization)
- Consolidate 17 useState into useReducer in sessions page
- Fix 18 .js extension imports across lib files
- Add type declarations for @rapideditor/country-coder
- Fix platform user types (PlatformUserRole enum)
- Fix Calendar component prop types
- Centralize next-auth type augmentation
- Add force-dynamic to all API routes (prevent build-time prerender)
- Fix Prisma JSON null handling with Prisma.DbNull
- Fix various type mismatches (SessionMessage, ImportRecord, etc.)
- Export ButtonProps from button component
- Update next-themes import path
- Replace JSX.Element with React.ReactElement
- Remove obsolete debug scripts and pnpm lockfile
- Downgrade eslint to v8 for next compatibility
2026-01-20 07:28:10 +01:00

1.2 KiB

title, impact, impactDescription, tags
title impact impactDescription tags
useLatest for Stable Callback Refs LOW prevents effect re-runs advanced, hooks, useLatest, refs, optimization

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:

function useLatest<T>(value: T) {
  const ref = useRef(value)
  useLayoutEffect(() => {
    ref.current = value
  }, [value])
  return ref
}

Incorrect (effect re-runs on every callback change):

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):

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])
}