// 前端：分开存储关联数据
const users = [
    { id: 1, name: '小明' },
    { id: 2, name: '小红' },
];

const orders = [
    { id: 101, user_id: 1, amount: 100, product: '键盘' },
    { id: 102, user_id: 2, amount: 200, product: '鼠标' },
    { id: 103, user_id: 1, amount: 150, product: '显示器' },
];

// 前端关联方式：find 串联
function getUserOrders(userId) {
    return orders.filter(o => o.user_id === userId);
}

// 要显示"用户名 + 订单信息"：
const result = orders.map(order => {
    const user = users.find(u => u.id === order.user_id);
    return {
        用户名: user?.name,
        商品: order.product,
        金额: order.amount,
    };
});