This a extending code with some modification from Promises/A+ implementation.

It is designed to get the basics spot on correct, so that you can build extended promise implementations on top of it.

API

var Promise = require('./promise');

var promiseSomeTask = new Promise(function (resolve, reject) {
    get('http://www.baidu.com', function (err, res) {
      if (err) reject(err);
      else resolve(res);
    });
  });

Inheritance

You can use inheritance if you want to create your own complete promise library with this as your basic starting point, perfect if you have lots of cool features you want to add. Here is an example of a promise library called Awesome, which is built on top of Promise correctly.

var Promise = require('./promise');
var factory = Promise.factory;

function Awesome(name) {
  if (!(this instanceof Awesome)) return new Awesome(fn);
  this.name = name;
  this.then = factory(name).then;
}

//Awesome extension
Awesome.prototype.spread = function (cb) {
  return this.then(function (arr) {
    return cb.apply(this, arr);
  })
};

N.B. if you fail to set the prototype and constructor properly or fail to do Promise.call, things can fail in really subtle ways.

License

MIT