Add days to date using javascript

Question

I am trying to add days to a given date using javascript. I have the following code

function onChange(e) {
    var datepicker = $(\"#DatePicker\").val();
           


        

Answer 1

I would like to encourage you to use DateJS library. It is really awesome!

function onChange(e) {
    var date = Date.parse($("#DatePicker").val()); //You might want to tweak this to as per your needs.
    var new_date = date.add(n).days();
    $('.new').val(new_date.toString('M/d/yyyy'); //You might want to tweak this as per your needs as well.
}

Answer 2

Date.prototype.addDays = function(days) {
    this.setDate(this.getDate() + days);
    return this;
};

and in your javascript code you could call

var currentDate = new Date();
// to add 8 days to current date
currentDate.addDays(8);

Answer 3

Try

function onChange(e) {
        var datepicker = $("#DatePicker").val();
        alert(datepicker);
        var parts = datepicker.split(/[^\d]/);
        var joindate = new Date();
        joindate.setFullYear(parts[2], parts[1]-1, parts[0]);
        alert(joindate);
        var numberOfDaysToAdd = 1;
        joindate.setDate(joindate + numberOfDaysToAdd);
        var dd = joindate.getDate();
        var mm = joindate.getMonth() + 1;
        var y = joindate.getFullYear();
        var joinFormattedDate = dd + '/' + mm + '/' + y;
        $('.new').val(joinFormattedDate);

    }

I suppose the problem is JavaScript expects format MM/DD/YYYY not DD/MM/YYYY when passed into Date constructor.

Answer 4

The first alert is the value of the field. the second is the generated date from a non-US formatted date.

Here is a working example

(seems that this kind of markup is necessary to get noticed)

If you want to keep your code, then you need to change

var joindate = new Date(datepicker);

to

var parms = datepicker.split("/");

then use

var joindate = new Date(parms[1]+"/"+parms[0]+"/"+parms[2]);

OR the identically working

var joindate = new Date(parms[2],parms[1]-1,parms[0]);

As pointed out in a few other answers too, use the .getDate()

joindate.setDate(joindate.getDate() + numberOfDaysToAdd);

Lastly you want to add a 0 if the month is < 10

if (mm<10) mm="0"+mm;

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If you are using the datepicker from jQuery UI, then you can do

$('.new').val($("#DatePicker").datepicker( "setDate" , +1 ).val());

instead of your function

http://jqueryui.com/demos/datepicker/#method-setDate

Sets the current date for the datepicker. The new date may be a Date object or a string in the current date format (e.g. '01/26/2009'), a number of days from today (e.g. +7) or a string of values and periods ('y' for years, 'm' for months, 'w' for weeks, 'd' for days, e.g. '+1m +7d'), or null to clear the selected date.