應該有更好的解 ,就提供給您參考看看~

 const userIds = ['U01', 'U02', 'U03'];
        const orderIds = ['T01', 'T02', 'T03', 'T04'];

        const userOrders = [
            {userId: 'U01', orderIds: ['T01', 'T02']},
            {userId: 'U02', orderIds: []},
            {userId: 'U03', orderIds: ['T03']},
        ];

        const userData = {
            'U01': 'Tom',
            'U02': 'Sam',
            'U03': 'John'
        };

        const orderData = {
            'T01': {name: 'A', price: 499},
            'T02': {name: 'B', price: 599},
            'T03': {name: 'C', price: 699},
            'T04': {name: 'D', price: 799}
        };
        console.log(
            userOrders.map((objs)=>{
                const result={};
                result.user={id:objs.userId,name:userData[objs.userId]};
                result.orders=objs.orderIds.map((orderId)=>{
                    const order={};
                    orderData[orderId].id=orderId;

                    return orderData[orderId];

                });
                return result
             })
        );

參考看看

為什麼我看不到題目，卻有兩位提供解答或回覆啊？
到底問題是什麼？