def-promise/src/index.js

A naive deferred promise, nothing more, nothing less.

/*
 * Copyright (c) 2021 Anton Bagdatyev (Tonix)
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * @type {WeakMap}
 */
const privateScope = new WeakMap();

export default class DefPromise extends Promise {
  constructor(executor = () => {}) {
    let resolve, reject;
    let isSettled = false,
      hasResolved = false,
      hasRejected = false;
    super((resolveFunc, rejectFunc) => {
      resolve = (...args) => {
        if (!isSettled) {
          isSettled = true;
          hasResolved = true;
        }
        resolveFunc(...args);
      };
      reject = (...args) => {
        if (!isSettled) {
          isSettled = true;
          hasRejected = true;
        }
        rejectFunc(...args);
      };
      executor(resolve, reject);
    });
    const priv = {
      resolve,
      reject,
      isSettled: () => isSettled,
      hasResolved: () => hasResolved,
      hasRejected: () => hasRejected,
    };
    privateScope.set(this, priv);
  }

  resolve(...args) {
    return privateScope.get(this).resolve(...args);
  }

  reject(...args) {
    return privateScope.get(this).reject(...args);
  }

  isSettled() {
    return privateScope.get(this).isSettled();
  }

  hasResolved() {
    return privateScope.get(this).hasResolved();
  }

  hasRejected() {
    return privateScope.get(this).hasRejected();
  }
}