React with Hooks, with Redux: reducer/index.js

index.js

const countReducer = (state = {count: 0}, action) => {
  switch(action.type) {
    case "INCREASE_COUNT":
      return {...state, count: action.payload}
    case "DECREASE_COUNT":
      return {...state, count: action.payload}
    case "RESET_COUNT":
      return {...state, count: action.payload}

    default:
      return state
  }
}

export default countReducer