Reduce context parameter

Andrea Giammarchi andrea.giammarchi at gmail.com
Mon Jan 7 15:25:55 PST 2013


not always, only when thisArg is needed ... Array#reduce(cb, initialValue[,
thisArg])

if needed, arr.reduce(cb, undefined, obj) does not look that bad, IMHO

again, I m fine with current status ...


On Mon, Jan 7, 2013 at 3:14 PM, Rick Waldron <waldron.rick at gmail.com> wrote:

>
>
> 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>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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