React Component w/ Function bind operator (https://github.com/zenparsing/es-function-bind)

gistfile1.js

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

  _onClick(e) {
    e.preventDefault();
    this.setState({clickCount: this.state.clickCount + 1});
  }

  render() {
    return (
      <button onClick={::this._onClick}>
        You have clicked me {this.state.clickCount} times
      </button>
    );
  }
}