/** * The `classList` utility creates a list of class names by joining an object's * keys, but only for values which are truthy. * * @example * classList({ foo: true, bar: false, qux: 'qaz' }); * // "foo qux" * * @param {Object} classes * @return {String} */ export default function classList(classes) { let classNames; if (classes instanceof Array) { classNames = classes.filter((name) => name); } else { classNames = []; for (const i in classes) { if (classes[i]) classNames.push(i); } } return classNames.join(' '); }