Learning Redux

Handling the undo/redo actions

Now all that's left to do is handling the undo/redo actions:

1. First, we import the UNDO and REDO action types:

import { INCREMENT, DECREMENT, RESET, UNDO, REDO } from '../actionTypes'

2. Then, we define some new cases in the switch statement, starting with the UNDO action type:

    case UNDO:

3. Again, we return a new state object based on the current state object:

return {       ...state,

4. However, this time, we only replace the currentState part, reducing the index by 1, if possible:

        currentState: currentState <= 0          ? currentState          : currentState - 1      }

5. Similarly, we handle the redo action, increasing the index by 1, if possible:

    case REDO:      return {        ...state,        currentState: currentState >= history.length - 1 ? currentState ...