如何在node express中获得像username.mywebsite.com或dashboard这样的路由

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

// 处理子域名路由
app.use((req, res, next) => {
  const subdomain = req.subdomains[0]; // 获取子域名
  req.username = subdomain.split('.')[0]; // 提取用户名
  next();
});

// 处理路由
app.get('/', (req, res) => {
  res.send(`Hello, ${req.username}!`);
});

// 启动服务器
app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

server {
  listen 80;
  server_name *.mywebsite.com;

  location / {
    proxy_pass http://localhost:3000;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
  }
}