Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.javascript > #20208

Re: Alignment of three tables

Show all headers | View raw

Evertjan. wrote:

> Thomas 'PointedEars' Lahn wrote on 11 jun 2013 in comp.lang.javascript:
>>> cells[j].style.width = "" + pwidths[j] + "%";
>> The algorithm for +  makes it unnecessary to concatenate "" here;
> 
> 'here' indeed.
> 
>> there is no preference in the algorithm towards left-to-right
>> conversion.
> 
> not quite correct, Thomas, there is a strong preference:
> 
> <script type='text/javascript'>
> 
> function f(x) {
>    document.write( x + '<br>' + typeof x + '<br><br>' );
> };
> 
> f( 4 + 4 + '5' ); // 85
> […]
> f( '4' + 4 + 5 ); // 455

JFTR:

It was rather obvious that I was talking about the algorithm for the 
(*binary*, as opposed to unary) “+” operator which only takes *two* 
operands.  I said, in essence, that because of

|   7. If Type(lprim) is String or Type(rprim) is String, then
|      a. Return the String that is the result of concatenating
|         ToString(lprim) followed by ToString(rprim)

*both*

  4 + "5"

and

  "4" + 5

result in

  "45"

which is a true statement.

This has nothing to do with the left-to-right evaluation order of 
expressions in these languages.  The expressions in your examples
are *several* “+” operations, and because of

| The production AdditiveExpression : AdditiveExpression +
| MultiplicativeExpression is evaluated as follows:
| 
|   1. Let lref be the result of evaluating AdditiveExpression.

  4 + 4 + '5'

is evaluated as

  (4 + 4) + "5"

leading to

  8 + "5"

and therefore

  "85"

Likewise,

  '4' + 4 + 5

is evaluated as

  ("4" + 4) + 5

leading to

  "44" + 5

and therefore

  "445"

∎

-- 
PointedEars

Twitter: @PointedEars2
Please do not Cc: me. / Bitte keine Kopien per E-Mail.

Back to comp.lang.javascript | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Alignment of three tables "Mel Smith" <med_cutout_syntel@aol.com> - 2013-06-09 08:49 -0600
  Re: Alignment of three tables Scott Sauyet <scott.sauyet@gmail.com> - 2013-06-09 08:18 -0700
  Re: Alignment of three tables Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-09 20:02 +0000
    Re: Alignment of three tables "Mel Smith" <med_cutout_syntel@aol.com> - 2013-06-09 15:01 -0600
      Re: Alignment of three tables Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-09 22:50 +0000
    Re: Alignment of three tables Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-10 00:46 +0200
      Re: Alignment of three tables John Harris <niam@jghnorth.org.uk.invalid> - 2013-06-10 14:41 +0100
        Re: Alignment of three tables Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-10 17:35 +0200
      Re: Alignment of three tables "Mel Smith" <med_cutout_syntel@aol.com> - 2013-06-10 09:08 -0600
        Re: Alignment of three tables "Mel Smith" <med_cutout_syntel@aol.com> - 2013-06-10 11:16 -0600
          Re: Alignment of three tables Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-11 02:05 +0000
            Re: Alignment of three tables Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-11 05:09 +0200
              Re: Alignment of three tables "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-06-11 10:59 +0200
                Re: Alignment of three tables Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-11 16:51 +0200
              Re: Alignment of three tables Stefan Weiss <krewecherl@gmail.com> - 2013-06-14 15:38 +0200
                Re: Alignment of three tables Eric Bednarz <bednarz@fahr-zur-hoelle.org> - 2013-06-14 20:26 +0200
                Re: Alignment of three tables Stefan Weiss <krewecherl@gmail.com> - 2013-06-14 21:22 +0200
                Re: Alignment of three tables Eric Bednarz <bednarz@fahr-zur-hoelle.org> - 2013-06-15 00:36 +0200
                Re: Alignment of three tables Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-15 12:04 +0200
                Re: Alignment of three tables Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-15 11:41 +0200
                Re: Alignment of three tables Stefan Weiss <krewecherl@gmail.com> - 2013-06-15 13:53 +0200
                Re: Alignment of three tables Scott Sauyet <scott.sauyet@gmail.com> - 2013-06-17 04:28 -0700
  Re: Alignment of three tables "Andy" <andy@NOSPAMmanyplay.com> - 2013-06-10 09:19 +0100
  Re: Alignment of three tables Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-06-12 18:56 +0100

csiph-web