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Groups > comp.lang.javascript > #18643
| Message-ID | <1542531.g9YUNRc4XZ@PointedEars.de> (permalink) |
|---|---|
| From | Thomas 'PointedEars' Lahn <PointedEars@web.de> |
| Organization | PointedEars Software (PES) |
| Date | 2013-02-26 18:07 +0100 |
| Subject | Re: Why is this returning NaN |
| Newsgroups | comp.lang.javascript |
| References | <kgi46g$ivc$1@dont-email.me> <timstreater-3655E3.12001626022013@news.individual.net> |
Tim Streater wrote:
> "Tony" <tony.johansson@inport.com> wrote:
>> var diff = Math.abs(new Date() - "2013/02/26 10:24:00");
>> This should be perfect legal I believe.
>
> […]
> 'new Date()' returns a reference to a Date object. What leads you to
> believe that you can subtract a string from a reference?
Theoretically it could be possible. Numerous other implicit type
conversions are being performed in ECMAScript, even some where primitive
types are being converted to object types (think about
String.prototype.replace(), or subtracting references to Date instances
which eventually subtracts the same values as the return values of the
getTime() methods of the referred objects, respectively).
However, whether type conversion is possible and whether it should be
possible are two different things. In this case, a future ECMAScript
implementation could specify that subtracting *from* a primitive string in
the ISO time format defined in the current Specification (ES 5.1) a
reference to a Date instance would convert the string value into a reference
to a corresponding Date by passing it to the Date constructor, and then
proceeding as if there had been two references to Date instances in the
first place. This would be unambiguous because of the “-” operation being
performed in the context of the Date instance reference instead of the
String value:
var diffMilliseconds = "2013-02-26T10:24:00" - new Date();
instead of
var diffMilliseconds = new Date("2013-02-26T10:24:00") - new Date();
Also, one could imagine a form of semantic coding found in e.g. POSIX
date(1) and MySQL where you would write
var d2 = d + "2 days";
instead of the not inelegant, but still too complicated
/* See ES 5.1, §§ 15.9.3.2, 9.1, and 8.12.8(!) */
var d2 = new Date(d);
d2.setDate(d2.getDate() + 2);
d2
One should probably have the ability of (perhaps restricted) operator
overloading in general, then, as in Python. This would be especially useful
with user-defined objects.
--
PointedEars
Twitter: @PointedEars2
Please do not Cc: me. / Bitte keine Kopien per E-Mail.
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Why is this returning NaN "Tony" <tony.johansson@inport.com> - 2013-02-26 11:54 +0100
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-02-26 12:09 +0100
Re: Why is this returning NaN "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2013-02-26 13:45 +0200
Re: Why is this returning NaN "J.R." <groups_jr-1@yahoo.com.br> - 2013-03-01 00:45 -0300
Re: Why is this returning NaN "J.R." <groups_jr-1@yahoo.com.br> - 2013-03-01 01:13 -0300
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-01 12:48 +0100
Re: Why is this returning NaN "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-03-01 10:06 +0100
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-01 12:46 +0100
Re: Why is this returning NaN John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-01 14:19 +0000
Re: Why is this returning NaN "Joao Rodrigues (J.R.)" <groups_jr-1@yahoo.com.br> - 2013-03-01 12:01 -0300
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-01 21:03 +0100
Re: Why is this returning NaN "Joao Rodrigues (J.R.)" <groups_jr-1@yahoo.com.br> - 2013-03-01 18:25 -0300
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-01 22:35 +0100
Re: Why is this returning NaN Patricia Shanahan <pats@acm.org> - 2013-03-01 20:31 -0800
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-02 12:49 +0100
Re: Why is this returning NaN "J.R." <groups_jr-1@yahoo.com.br> - 2013-03-03 12:32 -0300
Re: Why is this returning NaN "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-03-03 18:03 +0100
Re: Why is this returning NaN Martin Leese <please@see.Web.for.e-mail.INVALID> - 2013-03-03 10:16 -0700
OT: "javascript" was: Why is this returning NaN Christoph Becker <cmbecker69@gmx.de> - 2013-03-03 20:35 +0100
Re: OT: "javascript" was: Why is this returning NaN "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2013-03-03 21:43 +0200
Re: OT: "javascript" was: Why is this returning NaN Tim Streater <timstreater@greenbee.net> - 2013-03-03 19:45 +0000
"javascript" (was: OT: "javascript") Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-03 21:09 +0100
Re: "javascript" "J.R." <groups_jr-1@yahoo.com.br> - 2013-03-03 23:19 -0300
Re: "javascript" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-04 11:27 +0100
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-04 13:09 +0000
Re: "javascript" Christoph Becker <cmbecker69@gmx.de> - 2013-03-10 20:50 +0100
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-10 20:29 +0000
Re: "javascript" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-10 23:23 +0100
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-10 22:48 +0000
Re: "javascript" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-10 23:53 +0100
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-10 23:23 +0000
Re: "javascript" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-11 02:57 +0100
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-11 08:55 +0000
Re: "javascript" Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-11 17:38 +0100
Re: "javascript" Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-03-12 19:29 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-13 14:36 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-13 15:20 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-14 11:18 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-14 10:43 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-15 07:02 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-15 10:28 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-16 07:17 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-16 12:04 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-17 08:17 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-17 11:13 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-17 23:15 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-17 16:42 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-18 07:47 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-18 15:01 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-19 07:34 +1100
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-19 15:04 +0000
Re: "javascript" Andrew Poulos <ap_prog@hotmail.com> - 2013-03-20 07:40 +1100
Re: "javascript" Mike Duffy <Use.web.form@website_in_sig.com> - 2013-03-13 12:03 +0000
Re: "javascript" Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-03-14 21:22 +0000
Re: "javascript" Mike Duffy <Use.web.form@website_in_sig.com> - 2013-03-15 01:44 +0000
Re: "javascript" Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-03-16 19:42 +0000
Re: "javascript" Mike Duffy <Use.web.form@website_in_sig.com> - 2013-03-17 18:25 +0000
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-17 19:01 +0000
Re: "javascript" Gene Wirchenko <genew@telus.net> - 2013-03-15 10:55 -0700
Re: "javascript" John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-13 15:21 +0000
Re: "javascript" (was: OT: "javascript") Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-03-04 13:07 +0000
Re: "javascript" Christoph Becker <cmbecker69@gmx.de> - 2013-03-10 20:34 +0100
Re: "javascript" Tim Streater <timstreater@greenbee.net> - 2013-03-10 19:39 +0000
Re: OT: "javascript" was: Why is this returning NaN "J.R." <groups_jr-1@yahoo.com.br> - 2013-03-03 22:41 -0300
Re: OT: "javascript" was: Why is this returning NaN "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-03-04 09:57 +0100
Re: OT: "javascript" was: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-03-04 11:25 +0100
Re: OT: "javascript" was: Why is this returning NaN John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-04 14:52 +0000
Re: OT: "javascript" was: Why is this returning NaN Eric Bednarz <bednarz@fahr-zur-hoelle.org> - 2013-03-10 01:02 +0100
Re: OT: "javascript" was: Why is this returning NaN John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-10 10:52 +0000
Re: OT: "javascript" was: Why is this returning NaN Eric Bednarz <bednarz@fahr-zur-hoelle.org> - 2013-03-10 12:44 +0100
Re: OT: "javascript" was: Why is this returning NaN John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-10 17:49 +0000
Re: OT: "javascript" was: Why is this returning NaN Eric Bednarz <bednarz@fahr-zur-hoelle.org> - 2013-03-20 01:21 +0100
Re: OT: "javascript" was: Why is this returning NaN John G Harris <niam@jghnorth.org.uk.invalid> - 2013-03-20 15:25 +0000
Re: OT: "javascript" was: Why is this returning NaN Eric Bednarz <bednarz@fahr-zur-hoelle.org> - 2013-03-30 01:28 +0100
Re: Why is this returning NaN Tim Streater <timstreater@greenbee.net> - 2013-02-26 12:00 +0000
Re: Why is this returning NaN Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-02-26 18:07 +0100
Re: Why is this returning NaN Gregor Kofler <usenet@gregorkofler.com> - 2013-02-26 13:42 +0100
Re: Why is this returning NaN Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-02-27 20:43 +0000
Re: Why is this returning NaN "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-02-28 09:19 +0100
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