Our root reducers can reside in a reducers.js file. We are going to use the combinedReducers utility function from the Redux library:

import { combineReducers } from "redux";

import history from "utils/history";

export default function createReducer(injectedReducers = {}) {
 const rootReducer = combineReducers({
   ...injectedReducers
 });
 return rootReducer;
}