server.js

const express = require('express')
const next = require('next')

const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev })

const handle = app.getRequestHandler()

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

  server.all('*', (req, res) => {
    return handle(req, res)
  })

  const PORT = process.env.PORT || 3000
  server.listen(PORT, (err) => {
    if (err) {
      console.log(err)
    }
    console.log(`> Ready on port ${PORT}`)
  })
})