How Old Are You?

function howOld(dateString) {

    dateString = dateString.split('/');

    var today = new Date();
    var bday = new Date(parseInt(dateString[2]), parseInt(dateString[0]), parseInt(dateString[1]));

    var milliseconds =  today.getTime() - bday.getTime();
    var minutes = Math.round(milliseconds / (1000 * 60));
    var hours = Math.round(milliseconds / (1000 * 60 * 60));
    var days = Math.round(milliseconds / (1000 * 60 * 60 * 24));
    var months = Math.round(milliseconds / (1000 * 60 * 60 * 24 * (365.25 / 12.0)));

    return 'Months: ' + months + '\nDays: ' + days + '\nHours: ' + hours + '\nMinutes: ' + minutes;
}

console.log(howOld(prompt('What is your birthday?(MM/DD/YYYY)')));