Reduce context parameter

Rick Waldron waldron.rick at gmail.com
Mon Jan 7 15:14:10 PST 2013


On Monday, January 7, 2013, Andrea Giammarchi wrote:

> thisArg could have been third optional argument leaving current
> implementation as it is but making thisArg possible, IMHO
>
>
> lucky me I don't use Array#reduce that much neither I need the thisArg so
> far so ... OK for me
>

Sorry, but no—this would force user code to always provide an initialVal,
even when it would prefer to use the first item the array—which is the
default when initialVal is omitted.

Rick



>
> On Mon, Jan 7, 2013 at 2:59 PM, Rick Waldron <waldron.rick at gmail.com<javascript:_e({}, 'cvml', 'waldron.rick at gmail.com');>
> > wrote:
>
>>
>>
>> On Monday, January 7, 2013, Andrea Giammarchi wrote:
>>
>>> Rick you know bind is that slow and it costs on GC if used massively ;-)
>>>
>>
>> This is not my problem, implementors should optimize. bind() would only
>> occur once per method call.
>>
>>
>>>
>>> I use a lot the second argument in Array#extras and I feel Peter van der
>>> Zee here: reduce/Right should have had that too
>>>
>>
>> The initialVal argument is _optional_ and undefined is valid — how would
>> you decide if what was passed should be initial value or thisArg?
>>
>> Rick
>>
>>
>>
>>
>>
>>>
>>> br
>>>
>>
>>
>>
>>>
>>>
>>> On Mon, Jan 7, 2013 at 1:10 PM, Rick Waldron <waldron.rick at gmail.com>wrote:
>>>
>>>> I know this doesn't answer your question, but Function.prototype.bind
>>>> makes thisArg obsolete.
>>>>
>>>> Regarding the origin story, there is some discussion here:
>>>> https://mail.mozilla.org/pipermail/es-discuss/2008-June/006431.html
>>>>
>>>> Rick
>>>>
>>>>
>>>> On Mon, Jan 7, 2013 at 3:56 PM, Andrea Giammarchi <
>>>> andrea.giammarchi at gmail.com> wrote:
>>>>
>>>>> I think to increase confusion with other Array#extras :D
>>>>>
>>>>> and since we have this specced as it is now, a third parameter for the
>>>>> context could add even more confusion later on <3
>>>>>
>>>>> I know, I should not have answered that ...
>>>>>
>>>>>
>>>>> On Sun, Jan 6, 2013 at 9:48 AM, Peter van der Zee <ecma at qfox.nl>wrote:
>>>>>
>>>>>> Mostly out of curiosity; why do Array#reduce and reduceRight have no
>>>>>> context parameter?
>>>>>>
>>>>>> - peter
>>>>>> _______________________________________________
>>>>>> es-discuss mailing list
>>>>>> es-discuss at mozilla.org
>>>>>> https://mail.mozilla.org/listinfo/es-discuss
>>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>>
>>>>
>>>
>
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