decorator.js

function Sale(price){
    this.price = price;
    this.decorators_list = [];
}

Sale.decorators = {};

Sale.decorators.fedtax = {
    getPrice: function(price){
        return price * 2
    }
};

Sale.decorators.quebec = {
    getPrice: function(price){
        return price * 3
    }
};

Sale.decorators.money = {
    getPrice: function(price){
        return price * 4;
    }
};

Sale.prototype.decorate = function(decorator) {
    this.decorators_list.push(decorator);
};

Sale.prototype.getPrice = function(){
    var price = this.price,
                i,
                max = this.decorators_list.length,
                name;
    for(i = 0; i < max; i += 1){
        name = this.decorators_list[i];
        price = Sale.decorators[name].getPrice(price);
    }
    return price;
};

var sale = new Sale(100);
sale.decorate('fedtax');
sale.decorate('quebec');
sale.decorate('money');
sale.getPrice();

sample.js

function Parent(name){
    this.name = name || 'Adam';
}

Parent.prototype.say = function(){
    return this.name;
}

function Child(name){
    Parent.apply(this, arguments);
}

Child.prototype = new Parent();

var kid = new Child("Patrick");
console.log(kid.name);
console.log(kid.say());
delete kid.name;
console.log(kid.say());