events-autopromisify

Automatically promisifies all instance of [EventEmitter]'s .once() methods

Only promisifies .once() methods (and not .on()), as promises resolve only once.

https://nodejs.org/api/events.html

Install

npm i events-autopromisify

Usage

Just require it once before your main code

require('events-autopromisify')  // that's it

All subsequent EventEmitter instances will be automatically promisified

const {spawn} = require('child_process')

spawn(['cmd'])
  .on('stdout', () => { /* callbacks for .on() */ })
  .once('exit') // promises for .once()
  .then(...)

Watchout for 'error' events as they'll resolve by default, not reject.

const cp = spawn(['cmd']);

Promise.race([
  cp.once('exit'),
  cp.once('error').then(e => {throw e}),
])
.then(...).catch(...)