server.js

const dev = process.env.NODE_ENV !== 'production'
if (dev) {
  require('dotenv').config()
}
const next = require('next')
const routes = require('./routes')

const app = next({ dev })
const handler = routes.getRequestHandler(app)
const port = parseInt(process.env.PORT, 10) || 3000
const express = require('express')
const { join } = require('path')

app.prepare().then(() => {
  const server = express()

  server.get('/service-worker.js', (req, res) => {
    const filePath = join(__dirname, '.next', 'service-worker.js')
    return app.serveStatic(req, res, filePath)
  })

  server.get('/sitemap.xml', (req, res) => {
    const filePath = join(__dirname, 'static', 'sitemap.xml')
    return app.serveStatic(req, res, filePath)
  })

  server.use(handler)

  server.listen(port, (err) => {
    if (err) throw err
    console.log(`> Ready on http://localhost:${port}`)
  })
})