getDateForDateKey = (dateKey) => {
  const splittedDate = dateKey.split('-');
  return new Date(parseInt(splittedDate[0], 10), parseInt(splittedDate[1], 10) - 1, parseInt(splittedDate[2], 10));
}
Returns the date for a date string representation.

@param year {number} - any year
@param month {number} - can be between 1 and 12
@param day {number} - can be between 1 and 31 depending on the month
@returns {date} - the parse date