decorator_classic_oop_pattern_part_1.2.js

/**
 * ConcreteComponent
 * (класс для последующего декорирования)
 */
class Coffee {
	private cost:number = 1;
	getCost():number { return this.cost; }
}

abstract class CoffeeItem {
	protected cost:number;

	constructor(protected coffee:Coffee) {
	}

	public getCost():number {
		return this.coffee.getCost() + this.cost;
	}
}

/**
 * Decorator A
 */
class Milk extends CoffeeItem {
	protected cost = 0.5;
}

/**
 * Decorator B
 */
class Whip extends CoffeeItem {
	protected cost = 0.7;
}

/**
 * Decorator C
 */
class Sprinkles extends CoffeeItem {
	protected cost = 0.2;
}

function decorate(...args) {
	let newObj = args.shift();

	for (let obj of args) {
		if (typeof obj != 'function') continue;
		newObj = new obj(newObj);
	}

	return newObj;
}

var coffee = new Coffee();
var myCoffee = decorate(coffee, Milk, Whip, Sprinkles);
console.log(myCoffee.getCost());