ant-design/components/back-top/demo/custom.tsx

import React from 'react';
import { BackTop } from 'antd';

const style: React.CSSProperties = {
  height: 40,
  width: 40,
  lineHeight: '40px',
  borderRadius: 4,
  backgroundColor: '#1088e9',
  color: '#fff',
  textAlign: 'center',
  fontSize: 14,
};

const App: React.FC = () => (
  <div style={{ height: '600vh', padding: 8 }}>
    <div>Scroll to bottom</div>
    <div>Scroll to bottom</div>
    <div>Scroll to bottom</div>
    <div>Scroll to bottom</div>
    <div>Scroll to bottom</div>
    <div>Scroll to bottom</div>
    <div>Scroll to bottom</div>
    <BackTop>
      <div style={style}>UP</div>
    </BackTop>
  </div>
);

export default App;