[Nesquik]

function birthDateToAge(birthDate) {
	birthDate = new Date(birthDate);
	var now = new Date(),
	age = now.getFullYear() - birthDate.getFullYear();
        return now.setFullYear(1972) < birthDate.setFullYear(1972) ? age - 1 : age;
}

В safari - nan. Что делать?