Incorrect result in adding date

Question

r = new Date('Thu Aug 09 2018 22:25:07 GMT+0300');
k = new Date();
k.setDate(r.getDate() + 12);
$('#date_dep').val(k);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="date_dep" />

It works fine, but

var r = new Date('Thu Aug 09 2018 22:25:07 GMT+0300');
var k = new Date();
k.setDate(r.getDate() +12);
document.querySelector('#date_dep').value = k;

<input id="date_dep" readonly size="40">

returns wrong date. 'Thu Aug 09 2018 22:25:07 GMT+0300' is the only way i can get date

http://jsfiddle.net/aq9Laaew/120476/

Please see [*Why does Date.parse give incorrect results?*](https://stackoverflow.com/questions/2587345/why-does-date-parse-give-incorrect-results) — RobG, Jul 28 '18 at 22:15

Unmitigated · Answer 1 · 2018-07-28T22:16:54.287

2

The problem is that you are making a new Date to add days to instead of adding days to the date you created.

r= new Date('Thu Aug 09 2018 22:25:07 GMT+0300');
k=r;//sets k (the date to be changed) to the date you created above
k.setDate(r.getDate() +12);
$('#date_dep').val(k);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="date_dep" />

edited Jul 28 '18 at 22:16

answered Jul 28 '18 at 20:06

Unmitigated

76,500
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80

score 0 · Answer 2 · answered Jul 28 '18 at 20:00

0

I fixed your code using moment.js

var r = 'Thu Aug 09 2018 22:25:07 GMT+0300';
var d = moment(r);

k=new Date(d.format());
k.setDate(k.getDate() +12);
$('#date_dep').val(k);

http://jsfiddle.net/aq9Laaew/120508/

answered Jul 28 '18 at 20:00

Julien

903
7
12

1

This introduces a library and uses the built-in parser twice for no good reason. Posting the code here as a runnable snippet obviates the use of an external site. – RobG Jul 28 '18 at 22:14
I am usually all for moment/lodash/underscore etc but the majority of the cases on stackOverflow you would have to assume that people are `not` using any 3rd party libs. – Akrion Jul 29 '18 at 03:25

score 0 · Answer 3 · answered Jul 29 '18 at 03:22

You can simply achieve this with just one variable. Introducing the k causes confusion and leads to the actual issue.

r = new Date('Thu Aug 09 2018 22:25:07 GMT+0300');
r.setDate(r.getDate() +12);
$('#date_dep').val(r);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input id="date_dep" />

Incorrect result in adding date

3 Answers3