Node Promise + EventEmitter

future.js

module.exports = () => {
  // break resolve and reject out of a promise
  let resolve, reject;
  const promise = new Promise((res, rej) => {
    resolve = res;
    reject = rej;
  });

  // return as a future
  return {
    promise,
    resolve,
    reject,
  };
};

promise-emitter.js

const { EventEmitter } = require('events');
const createFuture = require('./future');

/**
 * PromiseEmitter class - Combines Promise and EventEmitter
 * @param {*} fn is a funtion that should accept (resolve, reject, emitter)
 */
function PromiseEmitter(fn) {
  const { resolve, reject, promise } = createFuture();
  
  // add eventemitter to promise
  Object.assign(promise, EventEmitter.prototype);
  EventEmitter.call(promise);
  
  // run fn call out of band
  setTimeout(() => fn.call(promise, resolve, reject, promise), 1);
  
  return promise;
}

module.exports = PromiseEmitter;