Sorting array of objects according to the date

You might be encountering an issue with new Date(...) not handling strings of this format since it's not a standard format. new Date("02-04-2020") interprets it as February 4, 2020, and new Date("16-04-2020") produces an error. It's seeming to use American date formats here, where we backwardsly use month before day.

If your dates were in the format yyyy-mm-dd, then new Date(...) would work properly, so if you're able to change that, that'll be the smoothest route. If you cannot change the format, you'll want to consider changing the sorting thusly:

const sorted_array = data
  .map(addSortableColumn)
  .sort(bySortColumn)
  .map(removeSortableColumn);

function addSortableColumn(item) {
  const [day, month, year] = item.date.split('-');
  return { ...item, _sortBy: year + month + day };
}

function bySortColumn(a, b) {
  return a._sortBy.localeCompare(b._sortBy);
}

function removeSortableColumn(item) {
  const { _sortBy, ...otherProps } = item;
  return otherProps;
}

(if you don't care about removing the sort column, you can skip that last step)

Update

If you need to preserve object prototypes, it was correctly pointed out that spread syntax destroys this. Another approach that I actually like even better is to store the sort columns in a separate map. The reason why it's even being stored is to avoid the sort keys needing to be computed multiple times.

const sortKeys = new Map();

const sorted_array = data.slice().sort(byDDMMYYYY);

function byDDMMYYYY(a, b) {
  return getSortKey(a).localeCompare(getSortKey(b));
}

function getSortKey(item) {
  let key = sortKeys.get(item);
  if (!key) {
    const [day, month, year] = item.date.split('-');
    key = year + month + day;
    sortKeys.set(item, key);
  }
  return key;
}