Groups > comp.lang.javascript > #19933

Re: !0 versus true

From	Daniel Pitts <newsgroup.nospam@virtualinfinity.net>
Newsgroups	comp.lang.javascript
Subject	Re: !0 versus true
References	<gMWdnU1mmO68hwPMnZ2dnUVZ_sqdnZ2d@westnet.com.au> <4493946.nSsM8AgQI3@PointedEars.de>
Message-ID	<a1Pnt.5879$OS5.4813@newsfe24.iad> (permalink)
Date	2013-05-24 12:17 -0700

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On 5/23/13 8:53 AM, Thomas 'PointedEars' Lahn wrote:
> Andrew Poulos wrote:
>
>> I'm working with some people who write code and minimises it. As ab
>> afterthought, I unminimise some of it and worked my way through it.
>>
>> One thing I found was that the minimiser had converted all instances of
>> true to !0.
>>
>> When I reported it no one thought it an issue as both true and !0 are
>> truthy. Should they be concerned?
>
> They should reconsider their approach as they are exchanging a minor
> increase in loading performance against a probably larger reduction of
> runtime performance, adding an operation (“!”) where there does not have to
> be one, just for the sake of two octets less per occurrence (“!0” vs.
> “true”).
>
> They should ask themselves instead why there were so many occurrences of
> ”true” in the code in the first place.  If I wrote a minimizer, *that* is
> where I would look first.  For example,
>
>    if (x == true)
>
> and
>
>    if (true == x)
>
> can be minimized to the equivalent, shorter, more efficient
>
>    if (x)
Yes, but if (x === true) can not be reduced to if (x).

Also, perhaps you're returning true after doing something that succeeded:

if (flibber()) { flub(); return true; }
if (flabber()) { noFlub(); return false; }

In these cases, reducing true and false to !0 and !!0 might make sense.

>
> This is easy to find and replace with regular expressions:
>
>    /* if (x) if (y) z; */
>    "if (x == true) if (true == y) z;"
>      .replace(/([^=])\s*==\s*true\b|\btrue\s*==\s*([^=])/g, "$1$2");
>
> or
>
>    /* if (x) if (y) z; */
>    "if (x == true) if (true == y) z;"
>      .replace(/([^=])\s*==\s*true\b|\btrue\s*==(?!=)\s*/g, "$1");
>
> or if the minimizer was Perl or PCRE-based, you could use negative
> lookbehind.  (Exceptions for String and RegExp literals not included.)
>
> Same for type-converting comparisons with “false” and negative type-
> converting comparisons with “true” and “false”.
>

Thread

!0 versus true Andrew Poulos <ap_prog@hotmail.com> - 2013-05-23 23:31 +1000
  Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-23 07:58 -0700
  Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-23 17:53 +0200
    Re: !0 versus true Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-05-24 12:17 -0700
      Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-24 21:56 +0200
        Re: !0 versus true Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2013-05-24 13:13 -0700
          Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-24 22:23 +0200
      Re: !0 versus true Denis McMahon <denismfmcmahon@gmail.com> - 2013-05-24 22:08 +0000
        Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-25 07:00 +0200
          Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-25 20:04 -0700
            Re: !0 versus true "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2013-05-26 11:07 +0200
            Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-26 13:11 +0200
              Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-26 13:28 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-27 12:07 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-27 11:27 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-27 23:30 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-27 17:12 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-28 02:40 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-27 20:29 -0700
                Re: !0 versus true John Harris <niam@jghnorth.org.uk.invalid> - 2013-05-28 15:38 +0100
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-28 08:32 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-28 21:14 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-28 15:38 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-29 13:20 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-29 06:37 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-29 16:28 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-29 13:32 -0700
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-29 23:34 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-30 06:30 -0700
                Re: !0 versus true John Harris <niam@jghnorth.org.uk.invalid> - 2013-05-29 17:33 +0100
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-29 11:34 -0700
                Re: !0 versus true John Harris <niam@jghnorth.org.uk.invalid> - 2013-05-31 10:22 +0100
                Re: !0 versus true Christoph Becker <cmbecker69@gmx.de> - 2013-05-31 13:04 +0200
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-31 18:13 +0200
                Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-31 18:16 +0200
                Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-05-31 07:25 -0700
  Re: !0 versus true imma harper <immaterial_uk@yahoo.co.uk> - 2013-05-31 09:46 -0700
    Re: !0 versus true Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-05-31 21:38 +0200
    Re: !0 versus true John Harris <niam@jghnorth.org.uk.invalid> - 2013-06-01 17:37 +0100
  Re: !0 versus true Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-06-02 21:03 +0100
    Re: !0 versus true Scott Sauyet <scott.sauyet@gmail.com> - 2013-06-03 04:45 -0700
      Re: !0 versus true Dr J R Stockton <reply1300@merlyn.demon.co.uk.invalid> - 2013-06-04 17:23 +0100

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