Redux localStorage Middleware

redux-localstorage-middleware.js

import R from 'ramda'

const defaultConfig = (config = {}) => {
  const {
    localStorage: storage = { removeItem: R.F },
    __APP_VERSION__: version = '',
  } = __BROWSER__ ? window : {}
  const namespace = 'my-cool-app'
  const appName = `${namespace}.v${version}`

  return {
    appName,
    blacklistActions: [/PENDING$/, /REJECTED$/],
    blacklistReducers: ['modals'],
    namespace,
    storage,
    version,
    ...config,
  }
}

export const persist = (opts) => {
  const {
    blacklistActions,
    blacklistReducers,
    storage,
    appName,
  } = defaultConfig(opts)
  const sanitize = R.compose(JSON.stringify, R.omit(blacklistReducers))
  const blacklist = R.flip(R.none)(blacklistActions)
  const passes = R.flip(R.test)
  const validAction = R.pipe(passes, blacklist)

  return R.curry((store, next, action) => {
    next(action)

    if (validAction(action.type)) {
      storage[appName] = sanitize(store.getState())
    }
  })
}

export const rehydrate = (opts) => {
  const { storage, appName, namespace } = defaultConfig(opts)
  const exp = new RegExp(namespace, 'g')
  const isCurrentVersion = R.equals(appName)
  const gotOldData = R.both(R.test(exp), R.complement(isCurrentVersion))
  const purge = R.bind(storage.removeItem, storage)

  R.forEach(R.ifElse(gotOldData, purge, R.F), R.keys(storage))

  return JSON.parse(storage[appName] || '{}')
}