Server.js

const TOP_PATHS = new Set(
  readdirSync(join(__dirname, '..', 'pages'))
    .map(f => f.replace(/\.js$/, ''))
    .concat(['', 'static', '_next'])
)



function topRoutesMiddleware(req, res, goNext) {
  const topPath = req.path.split('/', 2)[1]

  if (TOP_PATHS.has(topPath)) {
    const { path: pathname, query } = req
    handle(req, res, { pathname, query })
    return
  }

  goNext()
}