javascript sort by id

elems.sort((a, b) => a.id - b.id);function sortByDate( a, b ) {
  if ( a.created_at < b.created_at ){
    return -1;
  }
  if ( a.created_at > b.created_at ){
    return 1;
  }
  return 0;
}

myDates.sort(sortByDate);//myDates is not sorted.