Strategy

interface Pay {
    pay(price: number): number;
}

class NaverPay implements Pay {

    pay(price: number) {
        console.log('naver...');
        return price;
    }
}

class KaKaoPay implements Pay {

    pay(price: number) {
        console.log('kakao...');
        return price;
    }
}

class Payment {
    constructor(
        private readonly payment: Pay,
    ) {}

    pay(price: number) {
        return this.payment.pay(price);
    }
}

const nPay = new Payment(new NaverPay());

nPay.pay(1000);

const kPay = new Payment(new KaKaoPay());

kPay.pay(2000);