Create Redux store with Next.js

store.js

import {
 createStore, applyMiddleware, compose, combineReducers,
} from 'redux';
import thunkMiddleware from 'redux-thunk';
import reducer from '../modules/reducers';

let store = null;

const reducers = combineReducers(reducer);

const getStore = initialState => ({
  store: createStore(reducers, initialState, compose(applyMiddleware(thunkMiddleware))),
});
export const initStore = (isServer, initialState) => {
  if (isServer && typeof window === 'undefined') {
    // Server
    return getStore(initialState);
  }
  if (!store) {
    // Client
    store = getStore(initialState);
  }

  return store;
};

export default initStore;