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Groups > comp.lang.javascript > #26193
| From | Thomas 'PointedEars' Lahn <PointedEars@web.de> |
|---|---|
| Newsgroups | comp.lang.javascript |
| Subject | Re: Date arithmetic |
| Date | 2014-11-22 18:33 +0100 |
| Organization | PointedEars Software (PES) |
| Message-ID | <3141518.r5G2MTVnWM@PointedEars.de> (permalink) |
| References | (12 earlier) <5371045.XxPr97Xf0d@PointedEars.de> <40469088.RWZSUOfdCW@PointedEars.de> <QjocjrdDF3aUFwrA@invalid.uk.co.demon.merlyn.invalid> <1580490.WhVdJr593u@PointedEars.de> <e8GvEwN+N8bUFwS$@invalid.uk.co.demon.merlyn.invalid> |
Dr J R Stockton wrote:
> Thomas 'PointedEars' Lahn posted:
>> Dr J R Stockton wrote:
>>> Swifty already has his dates as yyyy-mm-dd. He can probably trust his
>>> browser to understand that (and can easily check),
>>> and he can append " GMT" to eliminate Summer Time worries.
>>> With a RegExp, one can easily check for the format ####-##-## and change
>>> the two '-' to '/' if desired and add the GMT bit.
>>
>> It is not logical to rely on probability, ambiguous or non-standard
>> formats, and use of additional features, when you can have certainty with
>> a standard approach and fewer requirements instead.
>
> But yyyy-mm-dd *IS* a standard format.
But “yyyy/mm/dd GMT” is not.
> It is in ECMA 5, too.
It is specified in _ECMA-262, Editions 5 and 5.1_. [0a][0b] But one has to
consider that
1. implementations have been written before Edition 5 which, as a result,
are not required to support the referred ISO 8601 formats in order to
be conforming;
2. not all implementations that claim conformance with Edition 5.x
are actually conforming;
3. there are implementations that partially implement a revision of
the Edition 6 draft, particularly current Google V8 JavaScript
(which I have found out recently by being surprised that
Object.keys(42) did _not_ throw a TypeError exception there, but
returned an empty Array [1][2a][2b]).
> But the only way in which he can be sure of what *his* browser does is to
> test it. For example, Safari 5.1.7 (2012) was presumably written with
> applicable standards, including /Inter Gravissimas/ and its relevant
> successors, in mind; however, it does not correctly implement the
> ordinary civil calendar.
But there is no need to test “new Date("yyyy-mm-dd")” and the like when you
can use Date.UTC(yyyy, +mm + 1, dd) instead which is more reliable than the
former in two respects:
1. You can be certain that each of the arguments passed will be considered
correctly because there is no additional parsing involved;
2. You can be certain that Daylight Saving Time switches are irrelevant,
regardless of the geographical location of the runtime environment,
because UTC does not include them.
According to my research, Date.UTC() was already specified by the first
Edition of ECMAScript. It is therefore reasonable to assume that it is
supported since Netscape JavaScript 1.1 and Microsoft JScript 1.0. [3] (The
ES Matrix does not include a test yet, for that reason.) Do you have reason
to believe otherwise?
> Can anyone test <http://www.merlyn.demon.co.uk/js-datex.htm#SB> in later
> Safari and report?
Probably. But superficial testing would be limited to the tested
environments and locations, thus not serve the argument that this would
generally be reliable, assuming all test results were positive. So there is
little point in testing.
>>> Note that such Date arithmetic can be unreliable near the International
>>> Date Line, because of occurrences such as the omission of 2011-12-30 Fr1
>>> by Samoa (non-US) and Tokelau.
>>
>> Which is why UTC should be used instead.
>
> […]
> Using UTC will be no help whatsoever in dealing with locations which
> have used or will use a discontinuous calendar in the interval in
> question.
It is the year 2014 of the Gregorian Calendar, we are talking about future
bookings, and “Swifty”’s holiday cottage is located near Bunessan, on the
Isle of Mull, Scotland, United Kingdom.
So much for *me* not “reading carefully”. I grant you detailed, maybe even
extensive, knowledge of timekeeping and related fields, but you fail in its
proper application.
______________
[0a] <http://ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262%205th%20edition%20December%202009.pdf>, p.
[0b] <http://ecma-international.org/ecma-262/5.1/#sec-15.9.3.2>
[1] <http://www.ecma-international.org/ecma-262/5.1/#sec-15.2.3.14>
[2a] <http://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.keys>
[2b] <http://PointedEars.de/es-matrix/?filter=Object\.keys&test=1>
[3] <http://ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,
%201st%20edition,%20June%201997.pdf>
--
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.
Back to comp.lang.javascript | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Date arithmetic Swifty <steve.j.swift@gmail.com> - 2014-11-11 12:38 +0000
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-11-11 15:10 +0100
Re: Date arithmetic Swifty <steve.j.swift@gmail.com> - 2014-11-11 22:07 +0000
Re: Date arithmetic Tim Streater <timstreater@greenbee.net> - 2014-11-11 22:37 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-12 02:40 +0100
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-11-12 08:21 +0100
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-13 15:27 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-13 21:26 +0100
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-14 14:16 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-15 07:13 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-15 19:36 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-16 17:24 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-16 18:49 +0100
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-17 00:14 +0100
Re: Date arithmetic Dr J R Stockton <J.R.Stockton@physics.org> - 2014-11-16 10:51 -0800
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-11-16 20:17 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-17 00:52 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-17 01:11 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-18 16:18 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-19 11:00 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-21 22:58 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-22 18:33 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-23 19:38 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-24 01:14 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-25 21:17 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-26 18:25 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-27 19:34 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-28 01:25 +0100
Re: Date arithmetic Dr J R Stockton <J.R.Stockton@physics.org> - 2014-11-28 05:29 -0800
Re: Date arithmetic Andrew Poulos <ap_prog@hotmail.com> - 2014-11-28 11:44 +1100
Re: Date arithmetic Dr J R Stockton <J.R.Stockton@physics.org> - 2014-11-28 04:52 -0800
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-28 14:24 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-28 14:47 +0100
Re: Date arithmetic Dr J R Stockton <J.R.Stockton@physics.org> - 2014-11-28 06:12 -0800
Re: Date arithmetic Andrew Poulos <ap_prog@hotmail.com> - 2014-11-29 16:59 +1100
Re: Date arithmetic John Harris <niam@jghnorth.org.uk.invalid> - 2014-11-29 20:05 +0000
Re: Date arithmetic Joao Rodrigues <groups_jr-1@yahoo.com> - 2014-11-29 23:47 -0200
Re: Date arithmetic Andrew Poulos <ap_prog@hotmail.com> - 2014-12-01 10:44 +1100
Re: Date arithmetic Tim Streater <timstreater@greenbee.net> - 2014-11-30 23:54 +0000
Re: Date arithmetic Andrew Poulos <ap_prog@hotmail.com> - 2014-12-01 13:01 +1100
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-17 01:34 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-17 01:41 +0100
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-18 19:06 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-18 16:26 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-19 17:52 +0100
Re: Date arithmetic Gene Wirchenko <genew@telus.net> - 2014-11-19 09:44 -0800
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-11-19 19:34 +0100
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-19 19:13 +0000
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-11-19 22:18 +0100
Re: Date arithmetic Gene Wirchenko <genew@telus.net> - 2014-11-19 13:43 -0800
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-19 22:40 +0000
Re: Date arithmetic Tim Streater <timstreater@greenbee.net> - 2014-11-19 22:51 +0000
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-19 23:35 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-19 23:10 +0100
Re: Date arithmetic Tim Streater <timstreater@greenbee.net> - 2014-11-19 22:32 +0000
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-19 23:26 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-20 00:47 +0100
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-20 00:17 +0000
Re: Date arithmetic Dr J R Stockton <J.R.Stockton@physics.org> - 2014-11-20 01:18 -0800
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-20 13:47 +0000
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-21 22:29 +0000
Re: Date arithmetic Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2014-11-19 19:24 -0200
Re: Date arithmetic Gene Wirchenko <genew@telus.net> - 2014-11-19 13:40 -0800
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-19 23:40 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-18 16:44 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-19 11:20 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-14 20:45 +0000
Re: Date arithmetic "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2014-11-15 14:13 -0800
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-15 23:42 +0100
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-11-12 00:23 +0100
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-12 13:24 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-12 14:43 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-12 19:48 +0100
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-13 01:18 +0100
Re: Date arithmetic Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-11-12 20:19 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-13 03:42 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-12 20:06 +0000
Re: Date arithmetic RobG <rgqld@iinet.net.au> - 2014-11-23 20:51 -0800
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-25 20:08 +0000
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-26 01:31 +0100
Re: Date arithmetic RobG <rgqld@iinet.net.au> - 2014-12-08 19:42 -0800
Re: Date arithmetic "Christoph M. Becker" <cmbecker69@arcor.de> - 2014-11-26 01:40 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-26 22:07 +0100
Re: Date arithmetic RobG <rgqld@iinet.net.au> - 2014-12-08 21:41 -0800
Re: Date arithmetic "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-12-09 09:47 +0100
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-12-09 14:17 +0100
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-12-10 23:34 +0000
Re: Date arithmetic RobG <rgqld@iinet.net.au> - 2014-12-10 17:21 -0800
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-12-13 17:19 +0000
Re: Date arithmetic RobG <rgqld@iinet.net.au> - 2014-12-10 18:35 -0800
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-11 22:29 +0100
Re: Date arithmetic Swifty <steve.j.swift@gmail.com> - 2014-11-11 21:53 +0000
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-11 23:43 +0100
Re: Date arithmetic John Harris <niam@jghnorth.org.uk.invalid> - 2014-11-12 15:49 +0000
Re: Date arithmetic Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-11-12 19:58 +0000
Re: Date arithmetic Dr.Kral@nyc.rr.com - 2014-11-13 20:24 -0500
Re: Date arithmetic Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-11-14 04:34 +0100
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