how to implement observer pattern in javascript?

Question

Hi I'm tyring to implement observer pattern in JavaScript:

My index.js:

$(document).ready(function () {
  var ironMan = new Movie();
  ironMan.setTitle('IronMan');
  ironMan.setRating('R');
  ironMan.setId(1);
  //  ironMan.setCast(['Robert Downey Jr.', 'Jeff Bridges', 'Gwyneth Paltrow']);

  var terminator = new Movie();
  terminator.setTitle('Terminator');
  terminator.setRating('P');
  terminator.setId(2);

  console.log(ironMan.toString());
  console.log(terminator.toString());

  ironMan.play();
  ironMan.stop();
  ironMan.download();
  ironMan.share('V. Rivas');

  console.log(ironMan.getCast()[0]);
});

My movie:

var title;
var rating;
var id;
var observers;


function Movie() {
  observers = new ObserverList();
}

//function Movie (title, rating, id){
//  this. title = title;
//  this.rating =  rating;
//  this.id =id;
//  observers = new ObserverList();
//}

Movie.prototype.setTitle = function (newTitle) {
  this.title = newTitle;
}

Movie.prototype.getTilte = function () {
  return this.title;
}

Movie.prototype.setRating = function (newRating) {
  this.rating = newRating;
}

Movie.prototype.getRating = function () {
  return this.rating;
}

Movie.prototype.setId = function (newId) {
  this.id = newId;
}

Movie.prototype.getId = function () {
  return this.id;
}

Movie.prototype.play = function () {
  for (i = 0; i < observers.Count; i++) {
    console.log("palying...");
  }
}

Movie.prototype.stop = function () {
  for (i = 0; i < observers.Count; i++) {
    console.log("stoped");
  }
}

Movie.prototype.AddObserver = function (observer) {
  observers.Add(observer);
};

Finally observer:

function ObserverList() {
  this.observerList = [];
}

ObserverList.prototype.Add = function (obj) {
  return this.observerList.push(obj);
};

ObserverList.prototype.Empty = function () {
  this.observerList = [];
};

ObserverList.prototype.Count = function () {
  return this.observerList.length;
};

ObserverList.prototype.Get = function (index) {
  if (index > -1 && index < this.observerList.length) {
    return this.observerList[index];
  }
};

ObserverList.prototype.Insert = function (obj, index) {
  var pointer = -1;

  if (index === 0) {
    this.observerList.unshift(obj);
    pointer = index;
  } else if (index === this.observerList.length) {
    this.observerList.push(obj);
    pointer = index;
  }

  return pointer;
};

Any help you can provide will me most grateful.

Answer 1

In JavaScript, there is no point to implement pure observer pattern as in Java, because JavaScript has this little thing called functional programming. So just use something like http://api.jquery.com/category/callbacks-object/ instead of your ObserverList.

If you still want to use your object, then everything depends on what do you want to pass to ObserverList.Add. If it is some object, then you need to write

for( i = 0; i < observers.Count; i++) { 
  observers[i].Notify("some data"); 
}

If it is a function then you need to write

for( i = 0; i < observers.Count; i++) { 
  observers[i]("Some data"); 
}

Also you can use Function.apply() or Function.call() to supply this to your function