手写简易 Redux

myRedux.js

function createStore(state, reducer) {
  const listeners = [];

  const getState = () => state;

  const dispatch = (action) => {
    state = reducer(state, action);
    listeners.forEach((item) => item());
  }

  const subscribe = (fn) => listeners.push(fn);

  return {
    getState,
    dispatch,
    subscribe,
  };
}

const reducer = (state, action) => {
  switch (action.type) {
    case 'UPDATE_NAME':
      return {
        ...state,
        name: action.payload,
      }
    case 'UPDATE_AGE':
      return {
        ...state,
        age: action.payload,
      }
    default:
      return state;
  }
};

const store = createStore({
  name: 'Jack',
  age: 18,
}, reducer);