javascript - Age calculation

Question

Having 2 javascript Dates,

first is birthdate and second is a date to calculate age from that date.

What should be the best way to do this.

Answer 1

function calculateAge (birthDate, otherDate) {
    birthDate = new Date(birthDate);
    otherDate = new Date(otherDate);

    var years = (otherDate.getFullYear() - birthDate.getFullYear());

    if (otherDate.getMonth() < birthDate.getMonth() || 
        otherDate.getMonth() == birthDate.getMonth() && otherDate.getDate() < birthDate.getDate()) {
        years--;
    }

    return years;
}

Example:

var age = calculateAge("02/24/1991", "02/24/2010"); // Format: MM/DD/YYYY

Answer 2

Here is a way:

function getAge(d1, d2){
    d2 = d2 || new Date();
    var diff = d2.getTime() - d1.getTime();
    return Math.floor(diff / (1000 * 60 * 60 * 24 * 365.25));
}
console.log( getAge(new Date(1978, 10, 3)) );

Be careful with the month. Javascript counts them from 0.
1978, 10, 3 means the November 3th, 1978