Re: Objects comparaison ?

From	"Jukka K. Korpela" <jkorpela@cs.tut.fi>
Newsgroups	comp.lang.javascript
Subject	Re: Objects comparaison ?
Date	2011-10-13 21:47 +0300
Organization	A noiseless patient Spider
Message-ID	<j77bob$rq6$1@dont-email.me> (permalink)
References	<1k93ek2.1xghqcy1upjvv5N%unbewusst.sein@fai.invalid>

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13.10.2011 21:20, Une Bévue wrote:

> if i do :
> var b = ({ 'huit': 8} == { 'huit': 8})? true : false;
>
> i get b = false

Yes, because each object literal creates a new object and a reference to it.

> however doing :
> var o = { 'huit': 8};
> b = (o == o)? true : false;
> gives obviously true meaning objects are compared by reference ?

You can say so if you like (stay tuned to the resident troll giving a 
pointless lecture on this), but basically what you are comparing here is 
values of expressions, and the value of "o" is the same as the value of 
"o", namely a reference to an object.

> not true for strings :
>
> var a = 'toto';
> var c = 'toto';
> var b = (a===c)? true : false;
>
> gives true...

Right, because strings are not objects. For strings, even the strict 
equality operator (===) is defined in terms of equality of characters 
(or, technically, the 16-bit values) in the strings. The types must 
match too, but two identical string literals compare as equal, and so do 
variables initialized by identical string literals.

> is there a function like equal for objects ???
> or does I need to implement it ?

If you wish to compare objects by equality of property values, you'll 
have to do it yourself (directly or via libraries). This is not quite as 
trivial as it may sound, as you need to decide whether it suffices that 
all properties of the first object exist in the second object too, with 
identical values (with some value for "identical"), or whether you also 
wish to require that the objects are intuitively copies of the same 
stuff, so that the second object has no properties that the first one 
hasn't.

-- 
Yucca, http://www.cs.tut.fi/~jkorpela/

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Objects comparaison ? unbewusst.sein@fai.invalid (Une Bévue) - 2011-10-13 20:20 +0200
  Re: Objects comparaison ? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2011-10-13 21:47 +0300
    Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-13 21:21 +0200
      Re: Objects comparaison ? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2011-10-13 22:40 +0300
        Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-13 21:46 +0200
          Re: Objects comparaison ? dhtml <dhtmlkitchen@gmail.com> - 2011-10-13 13:11 -0700
            Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-14 01:26 +0200
              Re: Objects comparaison ? dhtml <dhtmlkitchen@gmail.com> - 2011-10-14 12:41 -0700
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-15 21:37 +0200
                Re: Objects comparaison ? Antony Scriven <adscriven@gmail.com> - 2011-10-15 15:51 -0700
                Re: Objects comparaison ? dhtml <dhtmlkitchen@gmail.com> - 2011-10-15 21:28 -0700
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-16 11:41 +0200
                Re: Objects comparaison ? dhtml <dhtmlkitchen@gmail.com> - 2011-10-16 09:05 -0700
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-16 21:59 +0200
                Re: Objects comparaison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-17 10:53 +0100
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-17 07:02 -0700
                Re: Objects comparaison ? Andreas Bergmaier <andber93@web.de> - 2011-10-17 16:27 +0200
                Re: Objects comparaison ? dhtml <dhtmlkitchen@gmail.com> - 2011-10-17 21:28 -0700
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-18 11:12 +0200
                Re: Objects comparaison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-18 15:23 +0100
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-18 19:48 +0200
                Re: Objects comparaison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-19 17:08 +0100
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-20 23:58 +0200
                Re: Objects comparaison ? Antony Scriven <adscriven@gmail.com> - 2011-10-20 15:46 -0700
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-18 10:55 +0200
                Re: Objects comparaison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-18 15:59 +0100
                Re: Objects comparaison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-18 19:33 +0200
                Re: Objects comparaison ? Scott Sauyet <scott.sauyet@gmail.com> - 2011-10-18 14:05 -0700
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-18 16:51 -0700
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-18 17:21 -0700
                Re: Objects comparaison ? Scott Sauyet <scott.sauyet@gmail.com> - 2011-10-19 04:40 -0700
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-19 16:41 -0700
                Re: Objects comparaison ? Antony Scriven <adscriven@gmail.com> - 2011-10-19 17:14 -0700
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-19 18:33 -0700
                Re: Objects comparaison ? Scott Sauyet <scott.sauyet@gmail.com> - 2011-10-23 11:43 -0700
                Re: Objects comparaison ? Antony Scriven <adscriven@gmail.com> - 2011-10-19 15:32 -0700
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-19 16:54 -0700
                Re: Objects comparaison ? Antony Scriven <adscriven@gmail.com> - 2011-10-19 17:32 -0700
                Re: Objects comparaison ? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2011-10-19 18:39 -0700
                Re: Objects comparaison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-19 16:32 +0100
                Re: Objects comparaison ? Scott Sauyet <scott.sauyet@gmail.com> - 2011-10-19 14:18 -0700
                Re: Objects comparaison ? Antony Scriven <adscriven@gmail.com> - 2011-10-19 15:46 -0700
                Objects comparison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-20 16:28 +0100
                Re: Objects comparison ? Antony Scriven <adscriven@gmail.com> - 2011-10-20 12:23 -0700
                Re: Objects comparison ? Antony Scriven <adscriven@gmail.com> - 2011-10-20 15:04 -0700
                Re: Objects comparison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-21 15:38 +0100
                Re: Objects comparison ? Andreas Bergmaier <andber93@web.de> - 2011-10-22 19:40 +0200
                Re: Objects comparison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-23 11:49 +0100
                Re: Objects comparison ? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2011-10-24 19:00 +0200
                Re: Objects comparison ? Scott Sauyet <scott.sauyet@gmail.com> - 2011-10-21 05:29 -0700
                Re: Objects comparison ? John G Harris <john@nospam.demon.co.uk> - 2011-10-21 16:30 +0100
            Re: Objects comparaison ? Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2011-10-18 18:06 +0300
              Re: Objects comparaison ? Jake Jarvis <pig_in_shoes@yahoo.com> - 2011-10-18 17:43 +0200
      Re: Objects comparaison ? unbewusst.sein@fai.invalid (Une Bévue) - 2011-10-14 06:11 +0200
        Re: Objects comparaison ? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2011-10-14 08:07 +0300
          Re: Objects comparaison ? unbewusst.sein@fai.invalid (Une Bévue) - 2011-10-14 07:31 +0200
            Re: Objects comparaison ? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2011-10-14 08:59 +0300
              Re: Objects comparaison ? unbewusst.sein@fai.invalid (Une Bévue) - 2011-10-14 08:36 +0200
        Re: Objects comparaison ? unbewusst.sein@fai.invalid (Une Bévue) - 2011-10-14 08:35 +0200

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