Install

npm install --save react-bundle-util

Config for React Router

import get from 'react-bundle-util';

// local import
import Home from '../views/Home';

// routes for react-router with v4.
const routes = [
    {
        path: '/',
        exact: true,
        // sync module without code splitting.
        component: get(Home)
    }, {
        path: '/comment',
        // async module but not lazy load with code splitting.
        component: get(import('../views/Comment'))
    }, {
        path: '/detail/:id',
        // lazy load module with code splitting.
        component: get(resolve => require(['../views/Detail'], resolve))
    }, {
        path: '/list',
        // the export module is not the default.
        component: get(resolve => require(['../views/List'], module => resolve(module.List)))
    }
];

// export routes
export default routes;

Component for React Router

import React from 'react';
import ReactDOM from 'react-dom';
import {BrowserRouter, Route, Switch} from 'react-router-dom';

import get from 'react-bundle-util';

// local import
import Home from './views/Home';

// async module but not lazy load with code splitting.
const Comment = get(import('./views/Comment'));
// lazy load module with code splitting.
const Detail = get(resolve => require(['./views/Detail'], resolve));
// the export module is not the default.
const List = get(resolve => require(['./views/List'], module => resolve(module.List)));

class App extends React.Component {
    render() {
        return (
            <div>
                <Switch>
                    <Route path="/" exact component={Home}/>
                    <Route path="/comment" component={Comment}/>
                    <Route path="/detail/:id" component={Detail}/>
                    <Route path="/list" component={List}/>
                </Switch>
            </div>
        );
    }
}

ReactDOM.render(
    <BrowserRouter>
        <App/>
    </BrowserRouter>,
    document.getElementById('root')
);