test.js

const events = new require('events')
const { once } = events

const e = new events.EventEmitter()

main()

async function main () {
  await once(e, 'foo')
  console.log('foo was emitted')
  await once(e, 'bar')
  console.log('bar was emitted')
}


e.emit('foo')
e.emit('bar')