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Re: What's a good Javascript book?

Date 2012-10-10 06:44 +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> <Co2dnVSmOJ7VyunNnZ2dnUVZ_vGdnZ2d@earthlink.com> <1391239.xtCtL9uci3@PointedEars.de>
Message-ID <u9udnWjOFPbPlujNnZ2dnUVZ_sadnZ2d@earthlink.com> (permalink)

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Thomas 'PointedEars' Lahn wrote:
> Patricia Shanahan wrote:
> 
>> [An object] 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.
> 
> First of all, JavaScript is an implementation of ECMAScript.  One of many.  
> And ECMAScript gives its conforming implementations a wide latitude.  
> Ascribing features of the standard to the implementation of the standard and 
> vice-versa is the first capital beginner's mistake in this field:
> 
> <http://PointedEars.de/es-matrix>

While technically correct, this seems perhaps just a shade pedantic.
For example, most of the books that have been mentioned favorably in
this thread include the same beginner mistake in their titles.

> 
> The second one is ascribing features (and failings) of the host environment 
> API to the implementation or the standard.  You will find both often in 
> books and on Web sites actually not worth reading.
> 
>> 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.
> 
> Second, what has scope to do with the way objects are implemented?
> 

I meant scope in the generic sense of anything that affects which sets
of identifier-entity mappings have to be searched to find the meaning of
an identifier reference. That includes the prototype chain for a
reference in an object.

My main language implementation experience is with C and Fortran. C, in
particular, tends to have a very large set of global identifiers. I have
done performance measurement on identifier lookup in a C compiler I was
implementing. For that case, a hash table was a lot faster than a linked
list, and performance tuning the hash table got measurable improvements
in compile time.

Hash tables have a significant overhead in space and time, but O(1)
lookup complexity. Linked lists have very low overhead in both time and
space, but O(n) lookup complexity. The choice of which to use should be
based on the number of entries.

I don't see where a typical browser implementation of what is commonly
called JavaScript is going to get a large enough flat pool of
identifiers to make hashing worth while.

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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