第一步

const items2: MenuProps['items'] = [UserOutlined, LaptopOutlined, NotificationOutlined].map(
        (icon, index) => {
            const key = String(index + 1);

            return {
                key: `sub${key}`,
                icon: React.createElement(icon),
                label: `subnav ${key}`,

                children: new Array(4).fill(null).map((_, j) => {
                    const subKey = index * 4 + j + 1;
                    return {
                        key: subKey,
                        label: `option${subKey}`,
                    };
                }),
            };
        },
    );

第二步

<Sider className="site-layout-background" width={200}>
                    <Menu
                        mode="inline"
                        defaultSelectedKeys={['1']}
                        defaultOpenKeys={['sub1']}
                        style={{ height: '100%' }}
                        items={items2}
                    />
                </Sider>

ant design优化显示

前端项目实战13-ant design 侧边栏优化_官网

参考官网案例