React - Redux counter

redux로 counter만들기

counter.js

//액션 타입 만들기
const SET_DIFF = "counter/SET_DIFF";
const INCREASE = "counter/INCREASE";
const DECREASE = "counter/DECREASE";

//액션 생성함수 만들기
export const setDiff = (diff) => ({ type: SET_DIFF, diff });
export const increase = () => ({ type: INCREASE });
export const decrease = () => ({ type: DECREASE });

//초기 상태 선언
const initialState = {
  number: 0,
  diff: 1,
};

//리듀서 선언
export default function counter(state = initialState, action) {
  switch (action.type) {
    case SET_DIFF:
      return {
        ...state,
        diff: action.diff,
      };
    case INCREASE:
      return {
        ...state,
        number: state.number + state.diff,
      };
    case DECREASE:
      return {
        number: state.number - state.diff,
      };
    default:
      return state;
  }
}