How to get data from export?

Question

JavaScript

There are two files, here is the desired content:

import 'module-alias/register'
import 'source-map-support/register'
import runApp from '@/helpers/runApp'
import router from '@/helpers/runApp'
import runMongo from '@/helpers/mongo'

void (async () => {
  await runMongo()
  console.log('Mongo connected')
  await runApp()
})()

import file

export default async function () {
  const router = new Router()
  await bootstrapControllers({
    app,
    router,
    basePath: '/',
    controllers: [resolve(__dirname, '../controllers/*')],
    disableVersioning: true,
  })
  app.use(cors({ origin: '*' }))
  app.use(bodyParser())
  app.use(router.routes())
  app.use(router.allowedMethods())
  return new Promise<Server>((resolve, reject) => {
    const connection = app
      .listen(env.PORT)
      .on('listening', () => {
        console.log(`HTTP is listening on ${env.PORT}`)
        resolve(connection)
      })
      .on('error', reject)
  })
}

export from another file.
How to get data from export, and specifically access to the Router variable?