React Base Fiddle (JSX)

Starting point for creating JSFiddles with React.

HTML

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

Babel + JSX

class App extends React.Component {
  render() {
    return (<Child passing="I am being passed to child" />);
  }
}

class Child extends React.Component {
  constructor(props) {
    super(props)
      this.state = {
        passedProp: this.props.passing,
      }
  }

  render() {
      return (
          <React.Fragment>
            <button>{this.state.passedProp}</button>
          </React.Fragment>
      )
  }
}

ReactDOM.render(
  <App />,
  document.getElementById('container')
);