PureComponent.jsx

class CounterButton extends React.PureComponent {
  constructor(props) {
    super(props);
    this.state = {count: 1};
    this.handleClick = this.handleClick.bind(this);
  }
  
  handleClick() {
    this.setState(state => ({count: state.count + 1}));
  }

  render() {
    return (
      <button
        color={this.props.color}
        onClick={this.handleClick}>
        Count: {this.state.count}
      </button>
    );
  }
}