age-calculator-tepllo/index.js

Simple age calculator from birth date

function calculateAge(birthDate) {
  const today = new Date();
  const birth = new Date(birthDate);

  if (isNaN(birth)) {
    throw new Error("Invalid date format. Use YYYY-MM-DD");
  }

  let age = today.getFullYear() - birth.getFullYear();
  const m = today.getMonth() - birth.getMonth();
  if (m < 0 || (m === 0 && today.getDate() < birth.getDate())) {
    age--;
  }

  return age;
}

module.exports = { calculateAge };