promise_util

package.json

{
  "name": "promise_util",
  "version": "1.3.0",
  "main": "promise_util.js"
}

promise_util.js

const { createPromise, promiseResolve, promiseReject } = process.binding('util');
const { resolve: originalResolve, reject: originalReject } = Promise;
const Debug = require('vm').runInDebugContext('Debug');

(function() {
  if (Promise.create) return;

  Promise.create = createPromise;

  Promise.resolve = function(...args) {
    if (args.length === 2 && args[0] instanceof Promise) {
      return promiseResolve(args[0], args[1]);
    }
    return originalResolve.apply(this, args);
  };

  Promise.reject = function(...args) {
    if (arguments.length === 2 && args[0] instanceof Promise) {
      return promiseReject(args[0], args[1]);
    }
    return originalReject.apply(this, args);
  };
  
  Object.defineProperties(Promise.prototype, {
    info: { get() { return getPromiseInfo(this) } },
    isResolved: { get() { return this.info.status === 'resolved'; } },
    isRejected: { get() { return this.info.status === 'rejected'; } },
    isPending: { get() { return this.info.status === 'pending'; } },
  });

  Promise.prototype.resolve = function(x) {
    promiseResolve(this, x);
  };

  Promise.prototype.reject = function(x) {
    promiseReject(this, x);
  };

  Promise.delay = function(time) {
    const p = Promise.create();
    setTimeout(p.resolve.bind(p), time);
    return p;
  };
}());

function getPromiseInfo(promise) {
  let mirror = Debug.MakeMirror(promise, true);
  if (!mirror.isPromise()) return { status: 'resolved', value: arg };
  let status = mirror.status();
  if (status === 'pending') return { status };
  let value = mirror.promiseValue().value();
  return { status, value };
};