React路由器dom呈现空白页

import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';
import Home from './Home';
import About from './About';

function App() {
  return (
    <Router>
      <Switch>
        <Route exact path="/" component={Home} />
        <Route path="/about" component={About} />
      </Switch>
    </Router>
  );
}

import Home from './Home'; // 确保路径正确
import About from './About'; // 确保路径正确

<Route exact path="/" component={Home} />

const express = require('express');
const path = require('path');
const app = express();

app.use(express.static(path.join(__dirname, 'build')));

app.get('*', (req, res) => {
  res.sendFile(path.join(__dirname+'/build/index.html'));
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

npm install react-router-dom

import React from 'react';
import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';
import Home from './Home';
import About from './About';

function App() {
  return (
    <Router>
      <Switch>
        <Route exact path="/" component={Home} />
        <Route path="/about" component={About} />
      </Switch>
    </Router>
  );
}

export default App;