<div id="root"></div>
const App = () => {
  const [count, setCount] = React.useState(0);
  return (
    <div>
      <button onClick={() => setCount(count + 1)}>クリック {count} 回</button>
    </div>
  );
}
ReactDOM.render(<App />, document.getElementById("root"));
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External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/react/16.7.0-alpha.2/umd/react.production.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.7.0-alpha.2/umd/react-dom.production.min.js