SOURCE

class TrainOrder {
    create () {
        console.log('创建火车票订单')
    }
}
class HotelOrder {
    create () {
        console.log('创建酒店订单')
    }
}
 
class TotalOrder {
    constructor () {
        this.orderList = []
    }
    addOrder (order) {
        this.orderList.push(order)
        return this
    }
    create () {
        this.orderList.forEach(item => {
            item.create()
        })
        return this
    }
}
// 可以在购票网站买车票同时也订房间
let train = new TrainOrder()
let hotel = new HotelOrder()
let total = new TotalOrder()
total.addOrder(train).addOrder(hotel).create()