frontend/smart-hut/src/index.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';
import * as serviceWorker from './serviceWorker';
//React Router
import { BrowserRouter, Route, Switch } from "react-router-dom";

const routes = (
    <BrowserRouter>
      <Switch>
        <Route path="/" component={App} />
      </Switch>
    </BrowserRouter>
  );

ReactDOM.render(
    routes
    , document.getElementById('root'));
serviceWorker.unregister();