how to install react router dom in react code example

Example 1: npm react-router-dom

import React from "react";
import {
  BrowserRouter as Router,
  Switch,
  Route,
  Link,
  useRouteMatch,
  useParams
} from "react-router-dom";

export default function App() {
  return (
    
      

        

          

            Home
          
          

            About
          
          

            Topics
          
        

        
          
            
          
          
            
          
          
            
          
        
      
    
  );
}

function Home() {
  return 
Home
;
}

function About() {
  return 
About
;
}

function Topics() {
  let match = useRouteMatch();

  return (
    

      
Topics

      

        

          Components
        
        

          
            Props v. State
          
        
      

      {/* The Topics page has its own  with more routes
          that build on the /topics URL path. You can think of the
          2nd  here as an "index" page for all topics, or
          the page that is shown when no topic is selected */}
      
        
          
        
        
          
Please select a topic.
        
      
    
  );
}

function Topic() {
  let { topicId } = useParams();
  return 
Requested topic ID: {topicId}
;
}

Example 2: npm react router dom

// using ES6 modulesimport { BrowserRouter, Route, Link } from "react-router-dom"; // using CommonJS modulesconst BrowserRouter = require("react-router-dom").BrowserRouter;const Route = require("react-router-dom").Route;const Link = require("react-router-dom").Link;