Sorting date with javascript

sortDates.js

  let unsortedDates =
      ['2018-01-26',
          '2018-01-30',
          '2018-02-13',
          '2018-02-20',
          '2018-02-27',
          '2018-03-01',
          '2018-03-17',
          '2018-03-21',
          '2018-03-06',
          '2018-03-19',
          '2018-03-22'];

  // lets convert to Date object first
  unsortedDates = unsortedDates.map(date => new Date(date));
  // lets sort date now
  let sortedDates = unsortedDates.sort(function (a, b) {
      return a.getTime() - b.getTime()
  });

  // lets convert date object to date string
  sortedDates = sortedDates.map(x => x.getUTCFullYear() + "-" + (x.getUTCMonth() + 1) + "-" + x.getUTCDate());
  console.log(sortedDates)