guide/front/client/helpers/DeferredPromise.ts

export default class DeferredPromise {
  constructor () {
    this._promise = new Promise((resolve, reject) => {
      // assign the resolve and reject functions to `this`
      // making them usable on the class instance
      this.resolve = resolve
      this.reject = reject
    })
    // bind `then` and `catch` to implement the same interface as Promise
    this.then = this._promise.then.bind(this._promise)
    this.catch = this._promise.catch.bind(this._promise)
    this[Symbol.toStringTag] = 'Promise'
  }
}