Re: Difference between == and ===?

From	Norman Peelman <npeelmandog@cfl.rr.com>
Newsgroups	comp.lang.javascript
Subject	Re: Difference between == and ===?
Date	2012-06-05 23:16 -0400
Organization	A noiseless patient Spider
Message-ID	<jqmi38$d3m$1@dont-email.me> (permalink)
References	(15 earlier) <JRUUbNIW9zyPFwG+@J.A830F0FF37FB96852AD08924D9443D28E23ED5CD> <PjNch1HDZQzPFw9$@invalid.uk.co.demon.merlyn.invalid> <jql7em$9d0$1@news.albasani.net> <XnsA069CD919A8F5eejj99@194.109.133.133> <jqmf33$hre$1@news.albasani.net>

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On 06/05/2012 10:23 PM, BGB wrote:
> On 6/5/2012 1:12 PM, Evertjan. wrote:
>> BGB wrote on 05 jun 2012 in comp.lang.javascript:
>>
>>> FWIW, I had generally interpreted it more like:
>>> "null" means "there is no object here";
>>

   NULL is not an object, nor can it represent one.

>> "null" means a variable is not filled
>> with an allowed type value.
>>

   NULL does not define a type. NULL is nothing.

>> Not very usefull in JS variables,
>> but usefull for a numeric database field.
>>
>
> null seems "useful enough" IMO.
>
> it is useful for whenever a person wants a variable which "doesn't
> reference an object" or "doesn't represent a value".
>
>
>>
>>> "undefined" means "this value is not valid".
>>
>> "undefined" is a valid value of a variable in JS,
>> automagically assigned to a previously undefined variable,
>> and can be assigned to a existing variable.
>>
>
> an "invalid value" does not mean it can't be found in a variable (say,
> due to it being uninitialized), or assigned to a variable, but rather
> just that it *represents* an invalid value.
>

NULL literally means an absence of a value. It is not "" or 0 but will 
perform like a 0 in math computations (which may be un/desired).



-- 
Norman
Registered Linux user #461062
AMD64X2 6400+ Ubuntu 10.04 64bit

Thread

Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-28 20:19 -0700
  Re: Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-28 21:46 -0700
    Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-05-29 08:20 +0300
      Re: Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-29 07:56 -0700
        Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-05-29 19:15 +0300
          Re: Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-29 10:35 -0700
            Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-05-29 21:52 +0300
            Re: Difference between == and ===? Gregor Kofler <usenet@gregorkofler.com> - 2012-05-29 21:34 +0200
            Re: Difference between == and ===? Dr J R Stockton <reply1222@merlyn.demon.co.uk.not.invalid> - 2012-05-30 19:53 +0100
              Re: Difference between == and ===? Scott Sauyet <scott.sauyet@gmail.com> - 2012-05-31 04:52 -0700
                Re: Difference between == and ===? Dr J R Stockton <reply1222@merlyn.demon.co.uk.not.invalid> - 2012-06-01 21:41 +0100
    Re: Difference between == and ===? Gregor Kofler <usenet@gregorkofler.com> - 2012-05-29 09:34 +0200
      Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-05-29 14:13 +0200
        Re: Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-29 08:08 -0700
          Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-05-29 17:32 +0200
            Re: Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-29 08:50 -0700
          Re: Difference between == and ===? "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-05-29 16:26 +0000
            Re: Difference between == and ===? Jason Kim <iamjsonkim@gmail.com> - 2012-05-29 10:36 -0700
              Re: Difference between == and ===? Scott Sauyet <scott.sauyet@gmail.com> - 2012-05-29 10:52 -0700
              Re: Difference between == and ===? "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-05-29 21:50 +0000
                Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-05-30 07:46 +0300
                Re: Difference between == and ===? "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-05-30 07:48 +0000
                Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-05-30 11:08 +0300
                Re: Difference between == and ===? "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-05-30 14:36 +0000
                Re: Difference between == and ===? John G Harris <john@nospam.demon.co.uk> - 2012-05-30 15:26 +0100
                Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-05-30 20:17 +0300
                Re: Difference between == and ===? John G Harris <john@nospam.demon.co.uk> - 2012-06-01 14:54 +0100
                Re: Difference between == and ===? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-06-01 13:09 -0700
                Re: Difference between == and ===? Gene Wirchenko <genew@ocis.net> - 2012-06-01 13:49 -0700
                Re: Difference between == and ===? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-06-01 14:21 -0700
                Re: Difference between == and ===? John G Harris <john@nospam.demon.co.uk> - 2012-06-03 11:41 +0100
                Re: Difference between == and ===? Dr J R Stockton <reply1223@merlyn.demon.co.uk.not.invalid> - 2012-06-04 20:02 +0100
                Re: Difference between == and ===? BGB <cr88192@hotmail.com> - 2012-06-05 10:06 -0500
                Re: Difference between == and ===? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-06-05 18:12 +0000
                Re: Difference between == and ===? BGB <cr88192@hotmail.com> - 2012-06-05 21:23 -0500
                Re: Difference between == and ===? Norman Peelman <npeelmandog@cfl.rr.com> - 2012-06-05 23:16 -0400
                Re: Difference between == and ===? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-06-06 07:55 +0300
                Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-06 08:27 +0200
                Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-06 21:22 +0200
                Re: Difference between == and ===? Dr J R Stockton <reply1223@merlyn.demon.co.uk.not.invalid> - 2012-06-06 18:56 +0100
                Re: Difference between == and ===? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-06-07 07:12 +0000
                Re: Difference between == and ===? Dr J R Stockton <reply1223@merlyn.demon.co.uk.not.invalid> - 2012-06-08 20:11 +0100
                Re: Difference between == and ===? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-06-09 14:22 +0000
                Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-06 08:28 +0200
                Re: Difference between == and ===? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-06-06 09:51 +0000
                Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-06 21:22 +0200
                Re: Difference between == and ===? BGB <cr88192@hotmail.com> - 2012-06-06 08:35 -0500
                Re: Difference between == and ===? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-06 21:19 +0200
                Re: Difference between == and ===? John G Harris <john@nospam.demon.co.uk> - 2012-05-30 15:07 +0100
  Re: Difference between == and ===? John G Harris <john@nospam.demon.co.uk> - 2012-05-30 15:44 +0100
  Re: Difference between == and ===? Stefan Weiss <krewecherl@gmail.com> - 2012-06-01 10:05 +0200
    Re: Difference between == and ===? Ross McKay <au.org.zeta.at.rosko@invalid.invalid> - 2012-06-01 20:05 +1000
    Re: Difference between == and ===? "Evertjan." <exjxw.hannivoort@interxnl.net> - 2012-06-01 15:56 +0000

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