next.js/examples/with-pkg/server.js

const { createServer } = require('http')
const { parse } = require('url')
const next = require('next')

const port = parseInt(process.env.PORT, 10) || 3000
const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev, dir: __dirname })
const handle = app.getRequestHandler()

app.prepare().then(() => {
  createServer((req, res) =>
    handle(req, res, parse(req.url, true).pathname)
  ).listen(port, err => {
    if (err) throw err
    console.log(`> Ready on http://localhost:${port}`)
  })
})