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Groups > comp.lang.javascript > #24183

bitwise vs. logical OR operator (was: ISO 8601 Code Review Wanted)

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Evertjan. wrote:

> Christoph Michael Becker <cmbecker69@arcor.de> wrote on 16 mei 2014 in 
> comp.lang.javascript:
> 
>> Evertjan. wrote:
>>
>>> Christoph Michael Becker <cmbecker69@arcor.de> wrote on 15 mei 2014 in 
>>> comp.lang.javascript:
>>>
>>>> Furthermore there seems to be a bug at the end of setTime, where you're
>>>> using a | operator instead of || for the default of ss.
>>>
>>> alert(12|0) // 12
>>> alert(12|1) // 13 !
>>> alert(13|1) // 13
>>> alert('13'|1) // 13
>>> alert('13'|0) // 13
>>> alert('13x'|0) // 0 !
>>>
>>> alert(12||0) // 12
>>> alert(12||1) // 12 !
>>> alert(13||1) // 13
>>> alert('13'||1) // 13
>>> alert('13'||0) // 13
>>> alert('13x'||0) // 13x !
>>>
>>> methinks ss|0 is slightly better,
>>> as it zeros inconvertable strings.
>>
>> No, at least not in this case.
> 
> I was not talking about this special case.

Okay.  It wasn't clear to me because you had not changed the subject
line, and have been quoting the issue in the OP's code that I mentioned.

>> ss is either a string with exactly two
>> decimal digits or undefined (see the OP's full code[1]).  
> 
> In general one would consider all cases.

Not necessarily.  It depends on what one wants to achieve.

>> As you already
>> have examined, using the binary bitwise OR operator can lead to false
>> results, 
> 
> Not in the case of x|0, as it does not change any numeric x,
> and zeros all other x values. 

My bad.  Of course you're right wrt. to values that can be represented
as 32 bit integers.

> Now x||0 does not do that in the case that x is a string.
> 
>> while the binary logical OR operator is exactly what is
>> desired: use zero as default, when ss is falsy.
> 
> This NG is about javascript, I wish to discuss general cases.

However, whether the bitwise or the logical OR operator is correct (or
better suited) depends on the requirements.  These requirements have to
be stated, before a solution can be discussed.  It is not clear to me
which requirements you have in mind when suggesting using |0.
Converting a numeric argument to a number can also be done with

  +x

which obviously has different semantics, but might be preferable.

>> Using the binary logical operator for this purpose is a common ES idiom,
>> BTW.
> 
> What is ES?

An abbreviation of ECMAScript.

-- 
Christoph M. Becker

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Thread

ISO 8601 Code Review Wanted garrett.smith@acxiom.com - 2014-05-14 09:59 -0700
  Re: ISO 8601 Code Review Wanted John Harris <niam@jghnorth.org.uk.invalid> - 2014-05-15 10:15 +0100
    Re: ISO 8601 Code Review Wanted Christoph Michael Becker <cmbecker69@arcor.de> - 2014-05-15 21:31 +0200
      Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-15 12:53 -0700
        Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-15 13:12 -0700
        Re: ISO 8601 Code Review Wanted Christoph Michael Becker <cmbecker69@arcor.de> - 2014-05-15 22:21 +0200
          Re: ISO 8601 Code Review Wanted "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-05-16 00:44 +0200
            Re: ISO 8601 Code Review Wanted Christoph Michael Becker <cmbecker69@arcor.de> - 2014-05-16 01:26 +0200
              Re: ISO 8601 Code Review Wanted "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-05-16 09:39 +0200
                bitwise vs. logical OR operator (was: ISO 8601 Code Review Wanted) Christoph Michael Becker <cmbecker69@arcor.de> - 2014-05-16 12:50 +0200
                Re: bitwise vs. logical OR operator (was: ISO 8601 Code Review Wanted) dhtml <dhtmlkitchen@gmail.com> - 2014-05-16 11:21 -0700
  Re: ISO 8601 Code Review Wanted Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-05-16 22:26 +0100
    Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-19 11:56 -0700
      Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-19 17:03 -0700
        Re: ISO 8601 Code Review Wanted Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-05-21 17:30 +0100
          Re: ISO 8601 Code Review Wanted John Harris <niam@jghnorth.org.uk.invalid> - 2014-05-22 10:20 +0100
            Re: ISO 8601 Code Review Wanted Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-05-23 20:44 +0100
              Re: ISO 8601 Code Review Wanted John Harris <niam@jghnorth.org.uk.invalid> - 2014-05-24 15:54 +0100
          Re: ISO 8601 Code Review Wanted Tim Streater <timstreater@greenbee.net> - 2014-05-22 18:46 +0100
            Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-25 22:18 -0700
              Re: ISO 8601 Code Review Wanted Tim Streater <timstreater@greenbee.net> - 2014-05-26 11:41 +0100
                Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-28 09:54 -0700
          Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-23 10:37 -0700
            Re: ISO 8601 Code Review Wanted Dr J R Stockton <reply1400@merlyn.demon.co.uk.invalid> - 2014-05-24 19:09 +0100
  Re: ISO 8601 Code Review Wanted dhtml <dhtmlkitchen@gmail.com> - 2014-05-23 13:14 -0700

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