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

const animals = ["Cat", "Dog", "Rabbit"];

class RandomAnimal extends React.Component {
  constructor() {
    super();
    this.state = { animal: null };
    this.setRandomAnimal = this.setRandomAnimal.bind(this);
  }

  setRandomAnimal() {
    const animal = animals[Math.floor(Math.random() * 3)];
    this.setState({ animal });
  }

  render() {
    let renderAnimal;

    if (this.state.animal) {
      renderAnimal = <h1>Hello, {this.state.animal}</h1>
    }

    return (
    	<React.Fragment>
        <button onClick={this.setRandomAnimal}>Set Random Animal</button>
        { renderAnimal }
      </React.Fragment>
    )
  }
}

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