Implement extracting state logic #153

[mthanh2209]

In this section, I learned how to convert from useState to useReducer and how to use useReducer. 1. What a reducer function is?

• A reducer function is a pure function that takes in the current state and an action, and returns a new state based on that action.

2. How to refactor useState to useReducer?

• To refactor from useState to useReducer, follow these steps:
  • Move from setting state to dispatching actions.
  • Write a reducer function.
  • Use the reducer from your component.

3. When to use a reducer?

• When components have complex state logic that becomes hard to manage with useState.
• When want a centralized approach to manage state changes in a more predictable and controlled manner.

4. How to write one well?

• Reducers must be pure.
• Always return a new state object rather than modifying the existing state directly.
• Actions should have clear types and payloads, making it easy to understand how they modify the state.

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