Decorator 實作範例 2

decorator2.js

function Sale(price) {
  this.price = price || 100;
  this.decorators_list = [];
}

Sale.decorators = {};
Sale.decorators.fedtax = {
  getPrice: function(price) {
    return price + (price * 5/100);
  }
};

Sale.decorators.quebec = {
  getPrice: function(price) {
    return price + (price * 7.5/100);
  }
};

Sale.decorators.money = {
  getPrice: function(price) {
    return '$' + price.toFixed(2);
  }
};


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');
console.log(sale.getPrice());