class Example extends React.Component {
   constructor(props) {
      super(props);
      this.state = { count: 0 };
   }
   render() {
      return (<div><p>You clicked {this.state.count} times</p>
                          <button onClick={() => this.setState({ count: this.state.count + 1 })}>
               Click me
                          </button>
                </div>);
   }}