learning-redux-App-Reducer-ActionTypeSwitch.js

import React from 'react'
import { Provider } from 'react-redux'
import { createStore } from 'redux'
import CounterContainer from './Counter.container'

const initialState = {
  count: 0
}

function reducer(state = initialState, action) {
  switch (action.type) {
    case 'INCREMENT':
      return {
        count: state.count + 1
      }
    case 'DECREMENT':
      return {
        count: state.count - 1
      }
    default:
      return state
  }
}

const store = createStore(reducer)

const App = () => (
  <Provider store={store}>
    <CounterContainer />
  </Provider>
)

export default App