Simple Javascript Promise Implementation (see this blog post: http://www.opensourceconnections.com/2014/02/16/a-simple-promise-implementation-in-about-20-lines-of-javascript/)

promise.js

var Promise = function(wrappedFn, wrappedThis) {
  this.then = function(wrappedFn, wrappedThis) {
    this.next = new Promise(wrappedFn, wrappedThis);
    return this.next;
  };
    
  this.run = function() {
    wrappedFn.promise = this;
    wrappedFn.apply(wrappedThis);
  };
    
  this.complete = function() {
    if (this.next) {
      this.next.run();
    }
  };
};

Promise.create = function(func) { 
  if (func.hasOwnProperty('promise')) { 
    return func.promise;
  } else { 
    return new Promise();
  } 
};

sample usage

var foo = function() {
var promise = Promise.create(foo)
async.wait(function() {
promise.complete();
});
return promise;
}

Doesnt work. Can you please provide a full example?

foo = new Promise(function() {return [1,2,3,4];});

foo()

TypeError: object is not a function

Also doesnt work:

foo.then(function(i) {return i}).complete()