store.js

import { createReactNavigationReduxMiddleware } from 'react-navigation-redux-helpers'
import { createStore, applyMiddleware } from 'redux'
// #1. import redux-promise-middleware
import promiseMiddleware from 'redux-promise-middleware'
// #2. import redux-logger
import logger from 'redux-logger'

import reducers from './rootReducers'

const middleware = createReactNavigationReduxMiddleware(
  "root",
  state => state.nav,
)

const store = createStore(
  reducers,
  applyMiddleware(
    middleware,
    // #3. register promiseMiddleware and logger in our middleware
    promiseMiddleware(),
    logger
  ),
);

export default store