JS設計模式（一）--- 工廠模式

故事的開頭是這樣子的…
在很久很久以前，有一個學生叫小明
有一天，老師對小明，小明啊，你去給班上買一個籃球，一個足球，一套積木和一套樂高

class Good {
    constructor(name, price) {
        this.name = name;
        this.price = price;
    }
    showInfo() {
        console.log(`商品名：${this.name} 價格：￥${this.price}`);
    }
}

class Shop {
    constructor(customer) {
        this.customer = customer;
    }
    sell(good) {
        this.customer.buy(good);
        this.customer.total += good.price;
    }
}

class ToyShop extends Shop{
    constructor(customer) {
        super(customer);
    }
    sell(name) {
        switch(name) {
            case '樂高': super.sell(new Good('樂高', 3600));
            case '積木': super.sell(new Good('積木', 288));
        }
    }
}

class SportShop extends Shop{
    constructor(customer) {
        super(customer);
    }
    sell(name) {
        switch(name) {
            case '足球': super.sell(new Good('足球', 80));
            case '籃球': super.sell(new Good('籃球', 65));
        }
    }
}

class Student {
    constructor(name) {
        this.name = name;
        this.goodList = [];
        this.total = 0;
    }
    buy(good) {
        this.goodList.push(good);
    }
    getTotal() {
       console.log(`${this.name}一共花費了￥${this.total}`);
    }
}

於是，小明拿着錢，走在大街上…

let xiaoming = new Student('小明');

小明進了球具店，買了足球和籃球

let sportShop = new SportShop(xiaoming);
sportShop.sell('足球');
sportShop.sell('籃球');

小明進了文具店，買了樂高和積木

let toyShop = new ToyShop(xiaoming);
toyShop.sell('樂高');
toyShop.sell('積木');

小明結束了採購

xiaoming.getTotal();

小明並不關心每次購買的過程是怎樣的：商家庫存少了一個商品，商家盈利了多少錢，小明賬單上多了多少錢
小明只關注一件事情：商家賣出了一件商品給我