Prueba

observer.js

var Sinco = function(){};


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

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

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

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

ObserverList.prototype.removeAt = function(index){
    this.observerList.splice(index, 1);
}

ObserverList.prototype.indexOf = function(obj, startIndex){
    var i = startIndex;
    while(i < this.observerList.length){
        if(this.observerList[i]===obj){
            return i;
        }
        i++;
    }
    return -1;
}


var SincoObservable = function(obj, event){
    console.log("Creado observable");
    this.observers = new ObserverList();
}

SincoObservable.prototype.subscribe = function(observer){
    console.log("Bienvenido a la subscripción: " + observer);
    this.observers.add(observer);
}

SincoObservable.prototype.notify = function(context){
    var observerCount = this.observers.count();
    for(var i=0; i < observerCount; i++){
        this.observers.get(i)(context);
    }
}

SincoObservable.prototype.unSubscribe = function(observer){  }

function demo(data){
    this.name = data.name;
    this.update = function(){
        console.log("Actualizo -- " + this.name);
    }
}

var prueba = new demo({name:"Jairo Fernández"});
var observer1 = "Observer 1";

var observable = new SincoObservable(prueba, prueba.update); // Observar el objeto prueba y espero cambios de su funcion update

// El objeto observer1 va a suscribirse a el objeto observable
observable.subscribe(observer1);

prueba.update();