aureooms/js-set-partition

const isPartition = (elements, partition) => {
    const notyetseen = new Set(elements);

    for (const part of partition) {
        let partIsEmptySet = true;
        for (const element of part) {
            partIsEmptySet = false;
            if (notyetseen.has(element)) notyetseen.delete(element);
            else return false;
        }

        if (partIsEmptySet) return false;
    }

    return notyetseen.size === 0;
};

export default isPartition;