async.js

import {getStoredState, createPersistor, autoRehydrate } from 'redux-persist'

export async function bootstrap () {
  
  let initialState
  try {
    initialState = await getStoredState()
  } catch (err) {
    initialState = {}
  }
  
  const store = finalCreateStore(reducer, initialState)
  createPersistor(store)
  
  return store
}

callback.js

import {getStoredState, createPersistor, autoRehydrate } from 'redux-persist'

export function bootstrap (cb) {
  
  getStoredState(null, (err, initialState) => {
  
    const store = finalCreateStore(reducer, initialState)
    const persistor = createPersistor(store)
      
    cb(store)
  })
  
}