My quick deferred utility I seem to use everywhere

defer.js

/*
  Defer.js
  
  Usage:
    const myDefer = new Defer()
    myDefer.then(x => assert.equal(x, 1))
    myDefer.resolve(1)
*/

export default class Defer {
  constructor () {
    this.promise = new Promise((resolve, reject) => {
      this.resolve = resolve
      this.reject = reject
    })
  }
  
  then (...args) {
    return this.promise.then(...args)
  }
  
  catch (...args) {
    return this.promise.catch(...args)
  }
  
  finally (...args) {
    return this.promise.finally(...args)
  }
}