const App = () => {
  const handler = (event) => {
    event.preventDefault()
    window.alert('Click！');
  }

  return (
    <div>
      <a href="https://israynotarray.com/" onClick={ handler }>點我</a>
    </div>
  )
}

const app = document.querySelector('#app');
const root = ReactDOM.createRoot(app);
root.render(<App />);