import React, { Component } from 'react';
​
class Profile extends Component {
  constructor(props) {
    super(props);
    this.state = { isLiked: false };
  }
​
  componentDidMount() {
    console.log('Stateful component successfully mounted.');
  }
​
  _toggleLikeState = () => {
    this.setState({
      isLiked: this.state.isLiked
    });
  }
​
  render() {
    const { name } = this.props;
    const { isLiked } = this.state;
​
    return (
      <div>
        <h3>{ name }</h3>
        <span>{ isLiked ? 👍 : 👎 }</span>
        <button onClick={ this._toggleLikeState }>
          Toggle Like
        </button>
      </div>
    );
  }
}
​
​
HelloMessage.propTypes = { name: React.PropTypes.string };
HelloMessage.defaultProps = { name: 'World' };
​
ReactDOM.render(<Profile name="Alice" />, mountNode);