만나이 구하기

function getAge(todayString, dateString) {
    var today = new Date(todayString);
    var birthDate = new Date(dateString);
    var age = today.getFullYear() - birthDate.getFullYear();
    var m = today.getMonth() - birthDate.getMonth();
    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
        age--;
    }
    return age;
}
document.write('age: ' + getAge("2012/09/01", "1980/12/30"));
console.log('age: ' + getAge("2012/09/01", "1980/12/30"));