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Bug 1367013 - firefox's Date.toLocaleString() doesn't consider daylight saving time's in its calculations
Summary: firefox's Date.toLocaleString() doesn't consider daylight saving time's in it...
Alias: None
Product: Fedora
Classification: Fedora
Component: firefox
Version: 24
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: Jan Horak
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2016-08-15 09:09 UTC by Hedayat Vatankhah
Modified: 2016-08-25 09:40 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Last Closed: 2016-08-25 09:40:15 UTC

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Description Hedayat Vatankhah 2016-08-15 09:09:28 UTC
Description of problem:
Try when your system timezone is set to a timezone which has DST now. You'll see that "Locale String" line has a different time from the system time (even if your locale is set to en_US). For example, this is what I see in my system: (timezone is fake)

Time and date 	Mon Aug 15 2016 16:31:39 GMT+0730 (XXDT)
GMT'ed 	Mon, 15 Aug 2016 09:01:39 GMT
Locale String 	8/15/2016, 15:31:39 PM
Time-Zone offset 	-450 minutes

Version-Release number of selected component (if applicable):

How reproducible:

Additional info:
It seems to be a Fedora specific bug. Tests on Ubuntu with same firefox version seems to be OK.

Comment 1 Jan Horak 2016-08-23 13:52:34 UTC
Are you able to reproduce it with upstream binaries (

I cannot reproduce it with CEST time zone (my zone has DST now):

Time and date 	Tue Aug 23 2016 15:47:04 GMT+0200 (CEST)
GMT'ed 	Tue, 23 Aug 2016 13:47:04 GMT
Locale String 	8/23/2016, 3:47:04 PM 

For further investigation I would need your exact timezone.

Comment 2 Hedayat Vatankhah 2016-08-23 18:58:50 UTC
I'll check upstream binaries & let you know. A timezone in which the problem can be reproduced is IRDT time zone.

Comment 3 Jan Horak 2016-08-25 09:40:15 UTC
Thanks for the feedback. Interesting, I've found the reproducer. We're going to  move it to the upstream:

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