create-promise-callback.ts

type ThenableThenParameters<T> = Parameters<Promise<T>["then"]>;
type BroadcastFulfillment<T> = ThenableThenParameters<T>[0];
type BroadcastRejection = ThenableThenParameters<never>[1];

var resolved = Promise.resolve();

export function createPromiseAsync<T>(passResult: (promise: Promise<T>, ...args: ThenableThenParameters<T>) => void) {
  var promise = new Promise<T>(function (...args) {
    resolved.then(() => passResult(promise, ...args)) // queueMicrotask to make sure promise has been initialized
  });
};

export function createPromiseSync<T>(passResult: (promise: Promise<T>, ...args: ThenableThenParameters<T>) => void) {
  var arg: null | ThenableThenParameters<T> = null;
  var promise = new Promise<T>(function (...args) {
    arg = args
  });
  passResult(promise, ...<ThenableThenParameters<T>><unknown>arg)
};

export function createPromisePromised<T>() {
  return new Promise<{
    promise: Promise<T>;
    resolve: NonNullable<BroadcastFulfillment<T>>;
    reject: NonNullable<BroadcastRejection>
  }>(function (resolve) {
    var promise = new Promise<T>(function (broadcastFulfillment, broadcastRejection) {
      resolve(resolved.then(function () { // queueMicrotask to make sure promise has been initialized
        return {
          promise,
          resolve: broadcastFulfillment,
          reject: broadcastRejection
        };
      }))
    })
  })
};

export function createPromise<T>() {
  var res: BroadcastFulfillment<T> = null;
  var rej: BroadcastRejection = null;
  var promise = new Promise<T>(function (broadcastFulfillment, broadcastRejection) {
    res = broadcastFulfillment;
    rej = broadcastRejection
  });
  return {
    promise,
    resolve: res,
    reject: rej
  } as unknown as {
    promise: Promise<T>;
    resolve: NonNullable<BroadcastFulfillment<T>>;
    reject: NonNullable<BroadcastRejection>
  };
};