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Re: Difference between == and ===?

From BGB <cr88192@hotmail.com>
Newsgroups comp.lang.javascript
Subject Re: Difference between == and ===?
Date 2012-06-05 10:06 -0500
Organization albasani.net
Message-ID <jql7em$9d0$1@news.albasani.net> (permalink)
References (12 earlier) <jq5knk$a5h$1@dont-email.me> <1nBTslEYmMyPFwSi@J.A830F0FF37FB96852AD08924D9443D28E23ED5CD> <Wj9yr.13835$0x2.3107@newsfe13.iad> <JRUUbNIW9zyPFwG+@J.A830F0FF37FB96852AD08924D9443D28E23ED5CD> <PjNch1HDZQzPFw9$@invalid.uk.co.demon.merlyn.invalid>

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On 6/4/2012 2:02 PM, Dr J R Stockton wrote:
> In comp.lang.javascript message<JRUUbNIW9zyPFwG+@J.A830F0FF37FB96852AD0
> 8924D9443D28E23ED5CD>, Sun, 3 Jun 2012 11:41:26, John G Harris
> <john@nospam.demon.co.uk>  posted:
>
>> On Fri, 1 Jun 2012 at 13:09:25, in comp.lang.javascript, Daniel Pitts
>> wrote:
>>
>>   <snip>
>>> Imagine an "optional" parameter, but "null" is actually a valid value.
>>> undefined would mean "use the default", where "null" means "use-
>>> nothing".
>>
>> As I said, there can be circumstances where you need to tell null and
>> undefined apart. (Though I think it's unusual).
>
> N.B. undefined means "nothing has been written here", whereas null means
> "'_nothing_' HAS been written here".  One is a negative, the other a
> positive.
>


FWIW, I had generally interpreted it more like:
"null" means "there is no object here";
"undefined" means "this value is not valid".

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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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