Nodejs promises library based on promise.js

Today, I downloaded promise.js from the GIT repository, and found that the source code is written based on the Web front-end JavaScript, and cannot be used directly for nodejs. Fortunately, there's not a lot of code, and it's not very complicated. After analysis and integration, it is implemented as a nodejs framework, the code is as follows:

(function(){
/**
* Copyright 2012-2013 (c) Pierre Duquesne <stackp@online.fr>
* script: promise.js
* description: promises the nodejs The module 
* modified: https://github.com/stackp/promisejs
* authors: alwu007@sina.cn
* */

var Promise = exports.Promise = function(){
  this._callbacks = [];
};

Promise.prototype.then = function(func, context){
  //Method to handle the result of a callback
  function doCallbackResults(r) {
    if (r instanceof Promise) {
      r.then(function(err, values){
        p.done(err, values);
      });
    } else {
      p.done(null, r);
    }
  }

  var p = new Promise();
  if (this._isdone) {
    var results = func.apply(context, this.results);
    doCallbackResults(results);
  } else {
    this._callbacks.push(function(){
      var results = func.apply(context, arguments);
      doCallbackResults(results);
    });
  }
  return p;
};

Promise.prototype.done = function(){
  this.results = arguments;
  this._isdone = true;
  for (var i=0; i<this._callbacks.length; i++) {
    this._callbacks[i].apply(null, arguments);
  }
  this._callbacks = [];
};

Promise.join = function(promises){
  var p = new Promise();
  var results = [];

  if (!promises || !promises.length) {
    p.done(results);
    return p;
  }

  var numdone = 0;
  var total = promises.length;

  function notifier(i) {
    return function() {
      numdone += 1;
      results[i] = Array.prototype.slice.call(arguments);
      if (numdone === total) {
        p.done(results);
      }
    };
  }

  for (var i = 0; i < total; i++) {
    promises[i].then(notifier(i));
  }

  return p;
};

Promise.chain = function(funcs, args) {
  var p = new Promise();
  if (!funcs || !funcs.length) {
    p.done.apply(p, args);
  } else {
    funcs[0].apply(null, args).then(function(){
      funcs.splice(0, 1);
      Promise.chain(funcs, arguments).then(function(){
        p.done.apply(p, arguments);
      });
    });
  }
  return p;
};
})();

The attached test code is as follows:

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

function asyncfoo() {
  var p = new promise.Promise();
  setTimeout(function(){
    p.done();
  }, 1000);
  return p;
}

function syncfoo() {
  var p = new promise.Promise();
  p.done();
  return p;
}

var o = {};

function asyncfoo1(){
  var p = new promise.Promise();
  setTimeout(function(){
    p.done(null, 'Raymond');
  }, 1000);
  return p;
}

function asyncfoo2(err, name){
  o.name = name;
  var p = new promise.Promise();
  setTimeout(function(){
    p.done(null, 18);
  }, 1000);
  return p;
}
function asyncfoo3(err, age){
  o.age = age;
  var p = new promise.Promise();
  setTimeout(function(){
    p.done(null, 'boy');
  }, 1000);
  return p;
}
function asyncfoo4(){
  var p = new promise.Promise();
  setTimeout(function(){
    p.done(null, 'Hello, world!');
  }, 1000);
  return p;
}
promise.Promise.chain([asyncfoo1, asyncfoo2, asyncfoo3]).then(function(err, sex){
  o.sex = sex;
  return asyncfoo4();
}).then(function(err, say){
  o.say = say;
}).then(function(){
  console.dir(o);
});