classNames('unicorn', 'rainbow');
//=> 'unicorn rainbow'

classNames({awesome: true, foo: false}, 'unicorn', {rainbow: false});
//=> 'awesome unicorn'

classNames('unicorn', null, undefined, 0, 1, {foo: null});
//=> 'unicorn'

const buttonType = 'main';
classNames({[`button-${buttonType}`]: true});
//=> 'button-main'

const Button = props => {
	console.log(props);
	/*
	{
		type: 'success',
		small: true
	}
	*/

	const buttonClass = classNames(
		'button',
		{
			[`button-${props.type}`]: props.type,
			'button-block': props.block,
			'button-small': props.small
		}
	);

	console.log(buttonClass);
	//=> 'button button-success button-small'

	return <button className={buttonClass}>…</button>;
};