javascript create date from year, month, day

Question

I am trying to create a new date in javascript.

I have year, month and day. Following this tutorial, syntax for creating new date should be:

new Date(year, month, day, hours, minutes, seconds, milliseconds)

and that is exactly what I am doing:

var d = new Date(2016, 12, 17, 0, 0, 0, 0);

This should be december 17th 2016, but in my console output I see:

Tue Jan 17 2017 00:00:00 GMT+0100 (Central Europe Standard Time)

What am I doing wrong?

Months start from 0. You should use this: var d = new Date(2016, 11, 17); — Antonio, Dec 05 '16 at 19:40
In Javascript Date Object, months are 0 based. So 0 means January, 11 means December. try `var d = new Date(2016, 11, 17, 0, 0, 0, 0);` It should be fine. — Hiren, Dec 05 '16 at 19:42

score 103 · Answer 1 · edited Dec 05 '16 at 19:44

103

January is month 0. December is month 11. So this should work:

var d = new Date(2016, 11, 17, 0, 0, 0, 0);

Also, you can just simply do:

var d = new Date(2016, 11, 17);

edited Dec 05 '16 at 19:44

Drew13

answered Dec 05 '16 at 19:40

Dean Coakley

5

why the month is 0 based & year,day not – CMS Dec 24 '19 at 06:05
2

Seems it's just an old tradition that javascript copied from POSIX/Java. https://linux.die.net/man/3/localtime , http://web.mit.edu/java_v1.0.2/www/javadoc/java.util.Date.html#getMonth%28%29 – Dean Coakley Dec 28 '19 at 00:54
2

so confusing, I was wondering my weekOfYear() function returned 5 for January 1st – nipunasudha Nov 27 '20 at 02:20
If you've worked with languages where Arrays start from 1 it makes so much more sense – Oliver Dixon Jan 09 '23 at 13:14

Elias Soares · Accepted Answer · 2020-06-13T20:11:19.790

66

According to MDN - Date:

month

Integer value representing the month, beginning with 0 for January to 11 for December.

You should subtract 1 from your month:

const d = new Date(2016, 11, 17, 0, 0, 0, 0);

edited Jun 13 '20 at 20:11

answered Dec 05 '16 at 19:39

Elias Soares

1

The date constructor doesn't accept full years. If you plug in `2` for the year, you get `1902`. – Grant Gryczan May 03 '21 at 09:48
That's true, any Year before 100 will be prefixed with 19xx – Elias Soares May 03 '21 at 16:52
3

I found that you can use `new Date(0).setFullYear(year, month, day)` instead if `year` needs to be a full year – Grant Gryczan May 04 '21 at 12:27
Is there an underlying reason why the month is zero based (i.e. offset from the start of the year), and the day is not (an offset from the start of the month)? – Mark Roworth Aug 11 '21 at 19:17
Yes. It's some weird heritage from old languages that were used as base for JavaScript. See this answer https://stackoverflow.com/a/2552517/3429323 – Elias Soares Aug 12 '21 at 02:21

2 Answers2