compare-dates.js

const CompareDatesEnumType = 'equal' | 'first' | 'invalid' | 'second';
const CompareDatesEnum = {
  equal: 'equal',
  first: 'first',
  invalid: 'invalid',
  second: 'second',
};

const compareDates = (firstDate: string = '01.01.1970', secondDate: string = '01.01.1970'): CompareDatesEnumType => {
  const firstDateObject = new Date(dmyToMdyFormatter(firstDate));
  const secondDateObject = new Date(dmyToMdyFormatter(secondDate));
  if (isNaN(firstDateObject.getTime()) || isNaN(secondDateObject.getTime())) {
    return CompareDatesEnum.invalid;
  }
  if (firstDateObject > secondDateObject) {
    return CompareDatesEnum.first;
  }
  if (firstDateObject < secondDateObject) {
    return CompareDatesEnum.second;
  }
  return CompareDatesEnum.equal;
}