How to calculate age from jquery datepicker?

Question

I want to calculate age when date is selected by using jquery date picker. I added code below but it showing minus value if i select date like '19/03/2015','15/01/2015' or '19/03/2014' ,'31/12/2014'

  $(document).ready(function () 
{
 console.log($(document).width());           
     $('#patientDob').datepicker
    ({
        dateFormat: 'dd/mm/yy',
        changeMonth: true,
        changeYear: true,
        yearRange: '1900:2150',
        maxDate: new Date(),
        inline: true,

             onSelect: function() {
               var birthDay = document.getElementById("patientDob").value;
                var DOB = new Date(birthDay);
                var today = new Date();
                var age = today.getTime() - DOB.getTime();
                age = Math.floor(age / (1000 * 60 * 60 * 24 * 365.25));

                document.getElementById('patientAge').value = age;
            }
     });  

});

Answer 1

I have created this age calculator for my project using jQuery UI. and JavaScript function. you will get the exact result.

It it will calculate age and display as human readable. create a date field with ID 'datepicker'and import jquery and jquery ui . After that

Then just copy and paste the code to get the exact result.

output // 28 years 7 months 7 days

        $(function () {
        $("#datepicker").datepicker({
            changeMonth: true,
            changeYear: true,
            showAnim: 'slideDown',
            dateFormat: 'yy-mm-dd'
        }).on('change', function () {
            var age = getAge(this);
           /* $('#age').val(age);*/
            console.log(age);
            alert(age);

        });

        function getAge(dateVal) {
            var
                birthday = new Date(dateVal.value),
                today = new Date(),
                ageInMilliseconds = new Date(today - birthday),
                years = ageInMilliseconds / (24 * 60 * 60 * 1000 * 365.25 ),
                months = 12 * (years % 1),
                days = Math.floor(30 * (months % 1));
            return Math.floor(years) + ' years ' + Math.floor(months) + ' months ' + days + ' days';

        }

});

Answer 2

AFAIK The javascript Date requires yyyy/mm/dd, and you are sending:

 var DOB = new Date(birthDay); //  dateFormat: 'dd/mm/yy'

Change format to "yyyy/mm/dd" and will work ok.