Persist Redux in localStorage, with an expiration schedule for each store key.

persisted-timeboxed-redux-store.js

import { getInitialState, syncLocalStorageWithRedux } from './util-localStorage'

const reduxStorageKey = 'my-application:'
const ONE_SECOND = 1000
const ONE_MINUTE = ONE_SECOND * 60
const ONE_HOUR = ONE_MINUTE * 60
const ONE_DAY = ONE_HOUR * 24
const ONE_YEAR = ONE_DAY * 365

// create a white list.  key is the redux store key, and lifeSpan is 
// the length of time the value should be stored for in milliseconds. 
const reduxStorageWhiteList = [
  { key: 'user', lifeSpan: ONE_YEAR },
  { key: 'siteConfig', lifeSpan: ONE_DAY },
  { key: 'siteContent', lifeSpan: ONE_MINUTE * 5 }
]

const initialState = getInitialState(reduxStorageKey)
const store = createStore(initialState)

store.subscribe(() => syncLocalStorageWithRedux(reduxStorageKey, reduxStorageWhiteList, store.getState()))

util-localStorage.js

export const getInitialState = (storageKey) => {
  // iterate through local storage, and extract items whose key start with the storage key
  // check if they've expired.  if they haven't, add them to initial state.  If they have, delete them.
  // When we've iterated through all of them, return initial state.

  let initialState = {}

  Object.keys(window.localStorage).forEach(key => {
    const isPersistedItem = key.indexOf(storageKey) === 0
    const localSnapShot = isPersistedItem && JSON.parse(window.localStorage.getItem(key))
    const isAlive = localSnapShot && localSnapShot.timeOfDeath > Date.now()
    const isDead = localSnapShot && localSnapShot.timeOfDeath < Date.now()
    if (isAlive) {
      initialState[key.split(storageKey)[1]] = JSON.parse(localSnapShot.json)
    }
    if (isDead) {
      window.localStorage.removeItem(key)
    }
  })
  return initialState
}

export const syncLocalStorageWithRedux = (storageKey, whiteList, state) => {
  // iterate through our white list.
  // if the value hasn't been saved before, or the value in redux has
  // changed since the last time this was saved to local storage,
  // extend the life span and save the new value.

  whiteList.forEach(item => {
    const thisItemKey = storageKey + item.key
    const storeJSON = JSON.stringify(state[item.key])
    const storeSnapShot = JSON.stringify({ timeOfDeath: Date.now() + item.lifeSpan, json: storeJSON })

    const localSnapShot = window.localStorage.getItem(thisItemKey)
    const localSnapShotValue = localSnapShot && JSON.parse(localSnapShot)

    if (!localSnapShotValue || storeJSON !== localSnapShotValue.json) {
      window.localStorage.setItem(thisItemKey, storeSnapShot)
    }
  })
}