Example of reducer.js

import { GET_BLOGS_ERROR, GET_BLOGS_REQUEST, GET_BLOGS_SUCCESS } from './actions'
import { DATA_STATUS } from '../../consts/dataStatus'

const initialState = {
  blogsStatus: DATA_STATUS.NOT_TOUCHED,
  blogs: []
}

const blogsPageReducer = (state = initialState, action) => {
  switch (action.type) {
    case GET_BLOGS_REQUEST:
      return {
        blogsStatus: DATA_STATUS.REQUESTED
      }
    case GET_BLOGS_SUCCESS:
      return {
        blogsStatus: DATA_STATUS.SUCCESS,
        blogs: action.blogs
      }
    case GET_BLOGS_ERROR:
      return {
        blogsStatus: DATA_STATUS.ERROR,
        blogs: []
      }

    default:
      return state
  }
}

export default blogsPageReducer

Example of reducer.ts

import { DATA_STATUSES } from '../../../utils'
import * as authConstants from './constants'
import { actionType, AuthStateType, MainLeftMenuStateType } from './types'

const initialMainLeftMenuState: MainLeftMenuStateType = {
  currentState: DATA_STATUSES.UN_TOUCHED,
  isMenuOpen: false
}


export const mainLeftMenuState = (state: MainLeftMenuStateType = initialMainLeftMenuState, action: actionType) => {

  switch (action.type) {

    case authConstants.OPEN_MENU:
      return ({ ...state, currentState: action.data, isMenuOpen: true })

    case authConstants.CLOSE_MENU:
      return ({ ...state, currentState: DATA_STATUSES.UN_TOUCHED, isMenuOpen: false })

    default:
      return state
  }

}


const initialAuthState: AuthStateType = {
  isAuthorized: false,
  authStatus: DATA_STATUSES.UN_TOUCHED,
  resetPasswordStatus: DATA_STATUSES.UN_TOUCHED,
  registrationStatus: DATA_STATUSES.UN_TOUCHED
}


export const authState = (state: AuthStateType = initialAuthState, action: actionType) => {

  switch (action.type) {
    case authConstants.AUTH_REQUEST:
      return ({ ...state, authStatus: DATA_STATUSES.REQUESTING })
    case authConstants.AUTH_SUCCESS:
      return ({ ...state, authStatus: DATA_STATUSES.SUCCESS })
    case authConstants.AUTH_ERROR:
      return ({ ...state, authStatus: DATA_STATUSES.ERROR })

    case authConstants.REGISTRATION_REQUEST:
      return ({ ...state, registrationStatus: DATA_STATUSES.REQUESTING })
    case authConstants.REGISTRATION_SUCCESS:
      return ({ ...state, registrationStatus: DATA_STATUSES.SUCCESS })
    case authConstants.REGISTRATION_ERROR:
      return ({ ...state, registrationStatus: DATA_STATUSES.ERROR })

    case authConstants.RESET_PASSWORD_REQUEST:
      return ({ ...state, resetPasswordStatus: DATA_STATUSES.REQUESTING })
    case authConstants.RESET_PASSWORD_SUCCESS:
      return ({ ...state, resetPasswordStatus: DATA_STATUSES.SUCCESS })
    case authConstants.RESET_PASSWORD_ERROR:
      return ({ ...state, resetPasswordStatus: DATA_STATUSES.ERROR })

    default:
      return state
  }

}

redux thunk

import { call, put, takeEvery } from 'redux-saga/effects'
import API from '../../API'
import { GET_BLOGS_REQUEST, getBlogsError, getBlogsSuccess } from './actions'

export function* getBlogsRequestWorker() {
    try {
        const result = yield call(API.getBlogs);
        yield put(getBlogsSuccess(result));
      } catch (error) {
        yield put(getBlogsError());
      }
}

export function* getBlogsRequestWatcher() {
    yield takeEvery(GET_BLOGS_REQUEST, getBlogsRequestWorker);
}