Redux structure

actions.js

export default {
  ACTIONS_INC: state => ({
    ...state,
    count: state.count + 1
  }),
  ACTIONS_DEC: state => ({ ...state, count: state.count - 1 })
};

index.js

import { createStore, applyMiddleware } from "redux";
import reducer from "./reducer";
import middlewares from "./middlewares";
import initialState from "./initial-state";

const store = createStore(
  reducer,
  initialState,
  applyMiddleware(middlewares.log, middlewares.storage)
);

export default store;

initial-state.js

export default JSON.parse(localStorage.getItem("store")) || {
  count: 0,
  num: 0
};

middlewares.js

export default {
  log: store => next => action => {
    if (action.type === "ACTIONS_INC") {
      console.log("From middlewareLog", store.getState());
    }
    return next(action);
  },
  storage: store => next => action => {
    setTimeout(() => {
      localStorage.setItem("store", JSON.stringify(store.getState()));
    });
    return next(action);
  }
};

reducer.js

import actions from "./actions";

export default (state, { type }) => {
  let currentState = state;
  switch (type) {
    case "ACTIONS_INC":
      currentState = actions.ACTIONS_INC(state);
      break;
    case "ACTIONS_DEC":
      currentState = actions.ACTIONS_DEC(state);
      break;
  }
  return currentState;
};