ant-design/components/dropdown/demo/sub-menu-debug.tsx

import React from 'react';
import { DownOutlined } from '@ant-design/icons';
import type { MenuProps } from 'antd';
import { Dropdown, Space } from 'antd';

const items: MenuProps['items'] = [
  {
    key: '1',
    type: 'group',
    label: 'Group title',
    children: [
      {
        key: '1-1',
        label: '1st menu item',
      },
      {
        key: '1-2',
        label: '2nd menu item',
      },
    ],
  },
  {
    key: '2',
    label: 'sub menu',
    children: [
      {
        key: '2-1',
        label: '3rd menu item',
      },
      {
        key: '2-2',
        label: '4th menu item',
      },
    ],
  },
  {
    key: '3',
    label: 'disabled sub menu',
    disabled: true,
    children: [
      {
        key: '3-1',
        label: '5d menu item',
      },
      {
        key: '3-2',
        label: '6th menu item',
      },
    ],
  },
];

const App: React.FC = () => (
  <div style={{ height: 200 }}>
    <Dropdown menu={{ items, openKeys: ['2'] }} open autoAdjustOverflow={false}>
      <a onClick={(e) => e.preventDefault()}>
        <Space>
          Cascading menu
          <DownOutlined />
        </Space>
      </a>
    </Dropdown>
  </div>
);

export default App;