Using for await for listening to events; inspired by Deno's http module

event-utils.js

export async function * on (target, ...events) {
  const nextPromises = []
  let onFire
  
  function addNextPromise () {
    addNextPromise.push(new Promise(resolve => (onFire = resolve)))
  }
  addNextPromise()

  function listener (event) {
    onFire(event)
    addNextPromise()
  }

  for (const event of events) {
    target.addEventListener(event, listener)
  }

  while (true) {
    yield await new Promise(resolve => (onFire = resolve))
  }
}

export function once (target, event) {
  return new Promise(resolve => {
    target.addEventListener(event, resolve, { once: true })
  })
}

main.js

import { on, once } from './event-utils.js'

await once(document, 'DOMContentLoaded')

for await (const event of on(document.body, 'pointerdown', 'pointermove', 'pointerup')) {
  switch (event.type) {
    case 'pointerdown': {
      // ...
      break
    }
    case 'pointermove': {
      // ...
      break
    }
    case 'pointerup': {
      // ...
      break
    }
  }
}

This is flawed since it'll skip events if you await inside the for loop oof