React Router

import React from 'react';
import { render } from 'react-dom';
import Router from './components/Router';
import './css/style.css';
 
render( <Router />, document.querySelector( '#main' ) );

- index.js

import React from 'react';
import { BrowserRouter, Route, Switch } from 'react-router-dom';
import StorePicker from './StorePicker';
import App from './App';
import NotFound from './NotFound';
 
const Router = () => (
    <BrowserRouter>
        <Switch>
            <Route exact path="/" component={ StorePicker }  />
            <Route exact path="/store/:storeId" component={ App } />
            <Route exact component={ NotFound } />
        </Switch>
    </BrowserRouter>
)
 
export default Router;

- Router.js