react-avoid-unnecessary-effects

To avoid unnecessary useEffect in React, derive state during render using standard JavaScript, useMemo, or useSyncExternalStore, and handle updates through event handlers instead of effect-driven synchronization. This improves rendering speed.

Use useMemo for derived data in React when you need to cache expensive calculations between renders, whereas useEffect should be reserved for synchronizing with external systems, not for deriving state that can be calculated during render.

The best way to refactor React components is to replace useEffect-based state updates with render-time derivations, utilizing keys to reset state and event handlers for user actions to achieve faster frontend performance.

Yes, useSyncExternalStore replaces useEffect for external data subscriptions in React by providing a direct way to subscribe to external stores and trigger re-renders without writing manual effect-based synchronization logic.

Using useEffect for state derivation causes unnecessary React renders because it forces an extra render cycle after the initial paint to update state, whereas deriving state during render eliminates this extra cycle and improves performance.

Yes, you can use React keys to reset component state automatically when a prop changes, entirely avoiding the need for useEffect-based reset logic and keeping your component design cleaner and faster.