code-along.md

  import {createStore} from 'redux'

  const reducer = (state, action) => {
    switch (action.type) {
      case 'INCREMENT':
        return state = state + action.payload
      case 'DECREMENT':
        return state = state - action.payload
      default:
        return state
    }
  }

  const store = createStore(reducer, 0)

  store.subscribe(()=>{
    console.log('store changed', store.getState())
  })

  store.dispatch({type: 'INCREMENT', payload: 1})
  store.dispatch({type: 'DECREMENT', payload: 6})