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

        this.onClick = () => {
            this.setState((state, props) => {
                return {count: state.count + 1};
            });
        }
    }

    render() {
        return [
            <button key="1" onClick={this.onClick}>Update name</button>,
            <span key="2">{this.state.count}</span>
        ]
    }

    componentDidUpdate() {}
    getSnapshotBeforeUpdate() { return null }
}