ButtonGroup.jsx

import React from 'react';
import ReactDom from 'react-dom';

function Button({ children, onClick, type = 'button' }) { 
  return (
    <button type={type} className='btn' onClick={onClick} >
      {children}  
    </button>
  );
}

function ButtonGroup({ children, onClick }) {
  return (
    <div className='btn-group'>
      <Button onClick={onClick}>Click A</Button>
      <Button onClick={onClick}>Click B</Button>
      <Button onClick={onClick}>Click C</Button>
    </div>
  );
}

ReactDOM.render(
  <ButtonGroup onClick={() => console.log('You just clicked')} />,
  document.getElementById('root')
);