1106530 - Forefox 33.1.1 new Date("2014/01/01") return wrong date

Status: RESOLVED DUPLICATE of bug 1079720

(Core :: JavaScript: Standard Library, defect)

Description

[yaatmb]

User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:33.0) Gecko/20100101 Firefox/33.0
Build ID: 20141113143407

Steps to reproduce:

open console (F12)
input:
new Date("2014/01/01")


Actual results:

Date {Tue Dec 31 2013 23:00:00 GMT+0300}


Expected results:

Date {Wed Jan 01 2014 00:00:00 GMT+0400}

Comment 1

[Boris Zbarsky [:bzbarsky]]

Which timezone are you in?  What does 

  new Date("2014/01/01").getTimezoneOffset()

show?

Comment 2

[yaatmb]

new Date("2014/01/01").getTimezoneOffset()
shows:
-180

Comment 3

[Boris Zbarsky [:bzbarsky]]

OK.  So that's GMT+3, not surprising given the toString() output.  Again, what timezone are you in and why do you expect GMT+4 instead of GMT+3?

Comment 4

[yaatmb]

1. new Date("2014/01/01") must returns 01 January 2014
2. I'm from Russia (Moscow Timezone "RTZ 2"). Timezone in Moscow was changed [26 October 2014 02:00] from GMT+4 to GMT+3
3. I wrote about this bug in google chrome bugtracker, now google chrome in updated version work correctly.
And for example some results:
new Date("2014/01/01 00:59")
Date {Tue Dec 31 2013 23:59:00 GMT+0300} // wrong
new Date("2014/01/01 01:00")
Date {Wed Jan 01 2014 01:00:00 GMT+0400} // right
new Date("2003/01/01")
Date {Tue Dec 31 2002 23:00:00 GMT+0300} // wrong
new Date("2004/01/01")
Date {Thu Jan 01 2004 00:00:00 GMT+0300} // right
new Date("2020/01/01")
Date {Tue Dec 31 2019 23:00:00 GMT+0300} // wrong
new Date("2021/01/01")
Date {Fri Jan 01 2021 00:00:00 GMT+0300} // right
new Date("2025/01/01")
Date {Tue Dec 31 2024 23:00:00 GMT+0300} // wrong
new Date("2026/01/01")
Date {Thu Jan 01 2026 00:00:00 GMT+0300} // right
...

Chrome and Opera had the same problem in this years: 2003, 2014, 2020, 2025, etc.

Comment 5

[Boris Zbarsky [:bzbarsky]]

> 2. I'm from Russia (Moscow Timezone "RTZ 2"). Timezone in Moscow was changed [26 October
> 2014 02:00] from GMT+4 to GMT+3

Oh, and this was a permanent change, not DST?

Thank you for the additional testcases; the difference between "2014/01/01 01:00" and "2014/01/01" definitely looks fishy to me.

Jeff, do we use our own timezone database, or an OS-provided one?

Comment 6

[yaatmb]

Starting from October 26, 2014 02:00 Russia change dymanic DST to permanent. More info http://www.worldtimezone.com/dst_news/dst_news_russia-map-2014-07.html