playing with react

react-play-begin.js

class Button extends React.Component {
	constructor(props) {
  		super(props);
      this.state = { counter : 0 };
  }

	render() {
  	return (
    		<button onClick={this.handleClick}>{this.state.counter}</button>
    );
  }
  
  handleClick = () => {
  	this.setState(prevState => ({counter: ++prevState.counter}));
  }
}

ReactDOM.render(<Button />, mountNode);