$ npm install --save react-router-dom
// using ES6 modules
import { BrowserRouter, Route, Link } from "react-router-dom";
// using CommonJS modules
const BrowserRouter = require("react-router-dom").BrowserRouter;
const Route = require("react-router-dom").Route;
const Link = require("react-router-dom").Link;
<script src="https://unpkg.com/react-router-dom/umd/react-router-dom.min.js"></script>