combineReducers

export default theDefaultReducer = (state = 0, action) => state;

export const firstNamedReducer = (state = 1, action) => state;

export const secondNamedReducer = (state = 2, action) => state;


// rootReducer.js
import {combineReducers, createStore} from "redux";

import theDefaultReducer, {firstNamedReducer, secondNamedReducer} from "./reducers";

// Use ES6 object literal shorthand syntax to define the object shape
const rootReducer = combineReducers({
    theDefaultReducer,
    firstNamedReducer,
    secondNamedReducer
});

const store = createStore(rootReducer);
console.log(store.getState());
// {theDefaultReducer : 0, firstNamedReducer : 1, secondNamedReducer : 2}

import {combineReducers, createStore} from "redux";

// Rename the default import to whatever name we want. We can also rename a named import.
import defaultState, {firstNamedReducer, secondNamedReducer as secondState} from "./reducers";

const rootReducer = combineReducers({
    defaultState,                   // key name same as the carefully renamed default export
    firstState : firstNamedReducer, // specific key name instead of the variable name
    secondState,                    // key name same as the carefully renamed named export
});

const reducerInitializedStore = createStore(rootReducer);
console.log(reducerInitializedStore.getState());
// {defaultState : 0, firstState : 1, secondState : 2}