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Re: What's a good Javascript book?

Date 2012-10-09 17:56 +0100
From Patricia Shanahan <pats@acm.org>
Newsgroups comp.lang.javascript
Subject Re: What's a good Javascript book?
References <a30f024f-096a-48c2-a1fb-c1465c8e4267@googlegroups.com> <k4umv3$o27$1@news.albasani.net> <QzABPTFMH$cQFwLs@J.A830F0FF37FB96852AD08924D9443D28E23ED5CD>
Message-ID <Co2dnVSmOJ7VyunNnZ2dnUVZ_vGdnZ2d@earthlink.com> (permalink)

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John G Harris wrote:
> On Mon, 8 Oct 2012 at 16:11:47, in comp.lang.javascript, Stefan Weiss
> wrote:
> 
>   <snip>
>> (Objects may be implemented as some
>> form of hash table or hash map internally, but that's of no consequence
>> to users.)
>   <snip>
> 
> This is unlikely, as it happens.
> 
> One of the proposals for the abandoned ES4 was for 'for-in' to access
> properties in insertion order. Apparently enough web designers relied on
> this undocumented behaviour in NS and IE that it was thought worth
> standardising.
> 
> A hash table implementation would make this behaviour difficult to
> implement. Telling annoyed web designers whose pages stop working that
> it's their own fault for relying on undocumented behaviour has never
> been popular.

It could be implemented using a combined doubly linked list and hash
table, similar to Java's LinkedHashMap. Append each new entry to the
linked list, use the hash map to find entries, and update the linked
list when an item is removed. The linked list is used to iterate in
order of appearance.

However, JavaScript has a fairly complicated scope structure. Hash maps
for identifier lookup make most sense if there are a lot of identifiers
in one undifferentiated scope. Linked lists are faster and more compact
than hash maps for small numbers of entries.

Patricia

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Thread

What's a good Javascript book? I Am Here <iamhereintheworld@gmail.com> - 2012-10-08 06:35 -0700
  Re: What's a good Javascript book? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-10-08 13:52 +0000
    Re: What's a good Javascript book? "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2012-10-08 17:03 +0300
      Re: What's a good Javascript book? Tim Streater <timstreater@greenbee.net> - 2012-10-08 15:22 +0100
        Re: What's a good Javascript book? "Mel Smith" <med_cutout_syntel@aol.com> - 2012-10-08 08:56 -0600
  Re: What's a good Javascript book? Stefan Weiss <krewecherl@gmail.com> - 2012-10-08 16:11 +0200
    Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-09 10:43 +0100
      Re: What's a good Javascript book? Stefan Weiss <krewecherl@gmail.com> - 2012-10-09 13:12 +0200
        Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-10 15:32 +0100
          Re: What's a good Javascript book? Stefan Weiss <krewecherl@gmail.com> - 2012-10-10 20:13 +0200
            Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-11 14:28 +0100
      Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-09 17:56 +0100
        Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-10 00:32 +0200
          Re: What's a good Javascript book? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-10-09 16:37 -0700
          Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-10 06:44 +0100
            Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-10 20:09 +0200
            Re: What's a good Javascript book? Dr J R Stockton <reply1241@merlyn.demon.co.uk.invalid> - 2012-10-11 19:43 +0100
  Re: What's a good Javascript book? Gregor Kofler <usenet@gregorkofler.com> - 2012-10-08 16:21 +0200
  Re: What's a good Javascript book? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2012-10-08 07:56 -0700
  Re: What's a good [JavaScript] book? Matt McDonald <matt@fortybelow.ca> - 2012-10-08 11:38 -0400
    Re: What's a good [JavaScript] book? Matt McDonald <matt@fortybelow.ca> - 2012-10-08 11:42 -0400
      Re: What's a good [JavaScript] book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-10 00:41 +0200
  Re: What's a good Javascript book? Danny <dann90038@gmail.com> - 2012-10-08 11:57 -0700
    Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-08 20:39 +0100
  Re: What's a good Javascript book? I Am Here <iamhereintheworld@gmail.com> - 2012-10-09 06:19 -0700
    Re: What's a good Javascript book? Gregor Kofler <usenet@gregorkofler.com> - 2012-10-09 18:43 +0200
      Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-09 10:06 -0700
        Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-09 11:43 -0700
          Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-09 20:07 +0100
          Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-09 13:40 -0700
        Re: What's a good Javascript book? Gregor Kofler <usenet@gregorkofler.com> - 2012-10-09 20:55 +0200
          Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-09 13:45 -0700
          Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-10 04:31 -0700
      Re: What's a good Javascript book? Stefan Weiss <krewecherl@gmail.com> - 2012-10-09 20:09 +0200
        Re: What's a good Javascript book? Gregor Kofler <usenet@gregorkofler.com> - 2012-10-09 21:01 +0200
          Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-09 13:50 -0700
      Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-10 15:26 +0100
        Re: What's a good Javascript book? Tim Streater <timstreater@greenbee.net> - 2012-10-10 15:58 +0100
          Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-11 14:39 +0100
            Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-11 06:52 -0700
              Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-11 17:13 +0100
                Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-11 10:39 -0700
                Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-12 10:37 +0100
                Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-12 07:11 -0700
                Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-13 10:53 +0100
                Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-12 09:49 -0700
                Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-12 10:22 -0700
                Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-12 13:17 -0700
                Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-12 20:32 +0100
                Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-13 10:50 +0100
                Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-13 19:45 +0100
                Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-13 21:55 +0200
                Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-13 21:52 +0100
                Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-13 23:49 +0200
                Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-13 23:57 +0200
                Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-13 23:34 +0100
                Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-14 02:09 +0200
                Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-14 00:00 +0100
                Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-14 01:58 +0200
                Re: What's a good Javascript book? Patricia Shanahan <pats@acm.org> - 2012-10-14 07:17 +0100
                Re: What's a good Javascript book? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-10-15 01:17 +0200
                Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-14 13:40 +0100
                Re: What's a good Javascript book? Gene Wirchenko <genew@ocis.net> - 2012-10-14 19:03 -0700
                Re: What's a good Javascript book? John G Harris <john@nospam.demon.co.uk> - 2012-10-15 10:42 +0100
    Re: What's a good Javascript book? "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2012-10-09 22:49 +0200
  Re: What's a good Javascript book? Scott Sauyet <scott.sauyet@gmail.com> - 2012-10-09 12:00 -0700
  Re: What's a good Javascript book? I Am Here <iamhereintheworld@gmail.com> - 2012-10-16 06:57 -0700

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