ant-design/components/dropdown/demo/loading.tsx

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

const menu = (
  <Menu
    items={[
      {
        label: 'Submit and continue',
        key: '1',
      },
    ]}
  />
);

const App: React.FC = () => {
  const [loadings, setLoadings] = useState<boolean[]>([]);

  const enterLoading = (index: number) => {
    setLoadings(state => {
      const newLoadings = [...state];
      newLoadings[index] = true;
      return newLoadings;
    });

    setTimeout(() => {
      setLoadings(state => {
        const newLoadings = [...state];
        newLoadings[index] = false;
        return newLoadings;
      });
    }, 6000);
  };

  return (
    <Space direction="vertical">
      <Dropdown.Button type="primary" loading overlay={menu}>
        Submit
      </Dropdown.Button>
      <Dropdown.Button type="primary" size="small" loading overlay={menu}>
        Submit
      </Dropdown.Button>
      <Dropdown.Button
        type="primary"
        loading={loadings[0]}
        overlay={menu}
        onClick={() => enterLoading(0)}
      >
        Submit
      </Dropdown.Button>
      <Dropdown.Button
        icon={<DownOutlined />}
        loading={loadings[1]}
        overlay={menu}
        onClick={() => enterLoading(1)}
      >
        Submit
      </Dropdown.Button>
    </Space>
  );
};

export default App;