React useReducer Guide

useReducer is a powerful alternative to useState for complex state logic. Here's how to use it effectively.

Best Practices#

Reducer Design:
✓ Keep reducers pure
✓ Return new state objects
✓ Handle unknown actions gracefully
✓ Use action type constants

State Structure:
✓ Normalize nested data
✓ Keep state minimal
✓ Derive values when possible
✓ Initialize with all fields

Actions:
✓ Use descriptive action types
✓ Keep payload minimal
✓ Use action creators
✓ Document action shapes

Avoid:
✗ Side effects in reducers
✗ Mutating state directly
✗ Complex logic in components
✗ Over-engineering simple state

useReducer excels at managing complex state with clear action-based updates. Use it when state has multiple sub-values, when next state depends on previous state, or when you want testable, predictable state logic. Combine with Context for global state management, and use TypeScript for type-safe actions and state.

React useReducer Guide

Basic useReducer#

Action Payloads#

Lazy Initialization#

Complex State#

Form State Management#

Action Creators#

useReducer with Context#

TypeScript with useReducer#

useReducer vs useState#

Best Practices#

Conclusion#

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