ClassPropertiesBefore.jsx

class MyComponent extends React.Component {
    constructor(props) {
        this.state = {
            photoVisible: this.props.initialPhotoVisible
        };

        this.togglePhotoVisible = this.togglePhotoVisible.bind(this);
    }

    togglePhotoVisible() {
        this.setState({
            photoVisible: !this.state.photoVisible;
        });
    };

    render() {
        return (
            <div>
                <button onClick={this.togglePhotoVisible}>
                    {this.state.photoVisible ? 'Hide' : 'Show'} photo
                </button>
                {this.state.photoVisible && <img src={this.props.photoUrl}} />}
            </div>
        );
    }
}

MyComponent.propTypes = {
    photoUrl: PropTypes.string,
    initialButtonVisible: PropTypes.bool
};

MyComponent.defaultProps = {
    photoUrl: '',
    initialButtonVisible: true
};