Calculate Age

// Method 1: Simple age calculation
function calculateAge(birthDate) {
    const today = new Date();
    let age = today.getFullYear() - birthDate.getFullYear();
    const monthDiff = today.getMonth() - birthDate.getMonth();
    
    if (monthDiff < 0 || (monthDiff === 0 && today.getDate() < birthDate.getDate())) {
        age--;
    }
    
    return age;
}

const birthDate = new Date('1990-05-15');
console.log('Age:', calculateAge(birthDate));

// Method 2: Age with months and days
function calculateAgeDetailed(birthDate) {
    const today = new Date();
    let years = today.getFullYear() - birthDate.getFullYear();
    let months = today.getMonth() - birthDate.getMonth();
    let days = today.getDate() - birthDate.getDate();
    
    if (days < 0) {
        months--;
        const lastMonth = new Date(today.getFullYear(), today.getMonth(), 0);
        days += lastMonth.getDate();
    }
    
    if (months < 0) {
        years--;
        months += 12;
    }
    
    return { years, months, days };
}

const ageDetailed = calculateAgeDetailed(birthDate);
console.log(`${ageDetailed.years} years, ${ageDetailed.months} months, ${ageDetailed.days} days`);

// Method 3: Age in different units
function ageInUnits(birthDate) {
    const today = new Date();
    const diff = today - birthDate;
    
    return {
        milliseconds: diff,
        seconds: Math.floor(diff / 1000),
        minutes: Math.floor(diff / (1000 * 60)),
        hours: Math.floor(diff / (1000 * 60 * 60)),
        days: Math.floor(diff / (1000 * 60 * 60 * 24)),
        weeks: Math.floor(diff / (1000 * 60 * 60 * 24 * 7)),
        months: Math.floor(diff / (1000 * 60 * 60 * 24 * 30.44)),
        years: Math.floor(diff / (1000 * 60 * 60 * 24 * 365.25))
    };
}

const ageUnits = ageInUnits(birthDate);
console.log('Age in units:', ageUnits);

// Method 4: Next birthday
function getNextBirthday(birthDate) {
    const today = new Date();
    const currentYear = today.getFullYear();
    let nextBirthday = new Date(currentYear, birthDate.getMonth(), birthDate.getDate());
    
    if (nextBirthday < today) {
        nextBirthday.setFullYear(currentYear + 1);
    }
    
    return nextBirthday;
}

const nextBirthday = getNextBirthday(birthDate);
console.log('Next birthday:', nextBirthday);

// Method 5: Days until birthday
function daysUntilBirthday(birthDate) {
    const nextBirthday = getNextBirthday(birthDate);
    const today = new Date();
    const diff = nextBirthday - today;
    return Math.ceil(diff / (1000 * 60 * 60 * 24));
}

console.log('Days until birthday:', daysUntilBirthday(birthDate));