next.js/examples/with-apollo-and-redux/lib/store.js

import { createStore, applyMiddleware } from 'redux'
import { composeWithDevTools } from 'redux-devtools-extension'
import thunkMiddleware from 'redux-thunk'

const exampleInitialState = {
  lastUpdate: 0,
  light: false,
  count: 0
}

export const actionTypes = {
  ADD: 'ADD',
  TICK: 'TICK'
}

// REDUCERS
export const reducer = (state = exampleInitialState, action) => {
  switch (action.type) {
    case actionTypes.TICK:
      return Object.assign({}, state, {
        lastUpdate: action.ts,
        light: !!action.light
      })
    case actionTypes.ADD:
      return Object.assign({}, state, {
        count: state.count + 1
      })
    default:
      return state
  }
}

// ACTIONS
export const serverRenderClock = isServer => dispatch => {
  return dispatch({ type: actionTypes.TICK, light: !isServer, ts: Date.now() })
}

export const startClock = () => dispatch => {
  return setInterval(
    () => dispatch({ type: actionTypes.TICK, light: true, ts: Date.now() }),
    800
  )
}

export const addCount = () => dispatch => {
  return dispatch({ type: actionTypes.ADD })
}

export const initStore = (initialState = exampleInitialState) => {
  return createStore(
    reducer,
    initialState,
    composeWithDevTools(applyMiddleware(thunkMiddleware))
  )
}