Question

So, I have this code :

$('#end_date').click(function() 
{
    var start_date = new Date($('#start_date').val());
    var duration = parseInt($('#duration').val());

    var end_date = new Date();
    end_date.setDate(start_date + duration);

    $('#end_date').val($.datepicker.formatDate('yy-mm-dd', end_date));
});

Which, I believe, should take a start date from the form, and add some days (duration) in it, and the show the output in the other text field. However, the result I got is always NaN-NaN-NaN, or simply Invalid Date if I remove the formatting.

However :

$('#end_date').val($.datepicker.formatDate('yy-mm-dd', start_date));

works just fine. So I don’t think the problem lies in the 3rd line. And now I confused. Any pointer to solve this problem?

Answer 1

setDate just sets the day of the month, and you could use setFullYear and setMonth or you can do this.

$('#end_date').click(function() 
{
    var start_date = new Date($('#start_date').val());
    var duration = parseInt($('#duration').val());

    var end_date = new Date();
    end_date.setDate(start_date.getMilliseconds() + duration.getMilliseconds());

    $('#end_date').val($.datepicker.formatDate('yy-mm-dd', end_date));
});

Hoping that start_Date and duration are returning milliseconds.