Петр Мухуров

arr.reduce((acc, numbers, index) => {
  return index === 0 ? numbers : numbers.reduce((numAcc, num) => {
    return [...numAcc, ...acc.map(i => `${i}${num}`)]
  }, []);
}, []);

const getList = (data) => {
  let res = [];
  const toList = ({serve, name, children}, index, prefix = '') => {
	  const id = prefix ? prefix + '.' + (index + 1) : (index + 1);
	  res.push({id: id, serve: serve, name: name});
	  children && children.length > 0 && children.forEach((v, k) => toList(v, k, id));
  }

  data.forEach((item, key) => {toList(item, key)});

  return res;
}