Example

countReducer.js

// The action creator increaseBy is imported
// instead of the action's name from consts.js
import { increaseBy, decreaseBy } from './actions'

const deafaultCount = 100

export default countReducer = (count = deafaultCount, { payload, type }) => {
  switch(type){
// an action creator is used inside the reducer to get it's type
    case increaseBy.TYPE: {
      return count + payload
    }
// another action creator is used inside the reducer to get it's type
    case decreaseBy.TYPE: {
      return count - payload
    }
    default: {
      return count
    }
  }
}