Минимальная дата

const minDate = (…dates) => new Date(Math.min(…dates));

const dates = [
  new Date(2017, 4, 13),
  new Date(2018, 2, 12),
  new Date(2016, 0, 10),
  new Date(2016, 0, 9)
];
minDate(…dates); // 2016-01-08T22:00:00.000Z