redux-observable sessionStorage epic example

session.js

import { Observable } from 'rxjs'
import 'rxjs/add/observable/of'
import 'rxjs/add/operator/map'
import 'rxjs/add/operator/merge'
import { createAction } from 'redux-actions'

export const SESSION_STORAGE_KEY = 'SESSION_STORAGE_KEY'

export const GET_SESSION_REQUESTED = 'payout/GET_SESSION_REQUESTED'
export const GET_SESSION_FOUND = 'payout/GET_SESSION_FOUND'

export const SET_SESSION = 'payout/SET_SESSION'
export const SET_SESSION_SUCCEEDED = 'payout/SET_SESSION_SUCCEEDED'

export const getSession = createAction(GET_SESSION_REQUESTED)
export const getSessionFound = createAction(GET_SESSION_FOUND)

export const setSession = createAction(SET_SESSION)
export const setSessionSucceeded = createAction(SET_SESSION_SUCCEEDED)

export const getSessionEpic = (action$, store) => {
  return action$.ofType(GET_SESSION_REQUESTED)
    .switchMap(action => {
      /* eslint-env browser */
      const sessionString = sessionStorage.getItem(SESSION_STORAGE_KEY)
      let session
      try {
        session = JSON.parse(sessionString)
      } catch (e) {
        console.error(e)
      }

      // Dispatch session found only if session isn't empty(null)
      return Observable.of(getSessionFound(session)).filter(() => session !== null)
    })
}

export const setSessionEpic = (action$, store) => {
  return action$.ofType(SET_SESSION)
    .switchMap(action => {
      const session = JSON.stringify(action.payload)
      /* eslint-env browser */
      sessionStorage.setItem(SESSION_STORAGE_KEY, session)
      // Dispatch session found only if session isn't empty(null)
      return Observable.of(setSessionSucceeded(action.payload))
    })
}