[React] Increment Button Label On Click

gistfile1.txt

class Button extends React.Component {
	state = {counter : 0};

	changeLabel = () => {
  	this.setState({
    	counter: this.state.counter + 1
    })
  }

	render() {
  	return(
    	<button onClick={this.changeLabel}>
      	{this.state.counter}
      </button>
    )
  }
}

ReactDOM.render(<Button />, mountNode)