Trailing comma for function arguments and call parameters

Dmitry Soshnikov dmitry.soshnikov at gmail.com
Sun Aug 24 16:43:05 PDT 2014


On Mon, Jul 7, 2014 at 3:40 PM, Dmitry Soshnikov <dmitry.soshnikov at gmail.com
> wrote:

> On Sun, Jul 6, 2014 at 10:36 PM, Isiah Meadows <impinball at gmail.com>
> wrote:
>
>> My responses are inline.
>>
>> > From: Alex Kocharin <alex at kocharin.ru>
>> > To: Oliver Hunt <oliver at apple.com>, Dmitry Soshnikov <
>> dmitry.soshnikov at gmail.com>
>> > Cc: es-discuss <es-discuss at mozilla.org>
>> > Date: Sun, 06 Jul 2014 12:07:09 +0400
>> > Subject: Re: Trailing comma for function arguments and call parameters
>>
>> >
>> > In fact, how about the same syntax for arrays and function calls? With
>> trailing commas and elisions?
>> >
>> > So foo(1,,3,,) would be an alias for foo(1,undefined,3,undefined) ?
>> >
>> >
>> > 06.07.2014, 11:57, "Alex Kocharin" <alex at kocharin.ru>:
>> > > Unless you use leading comma style, trailing commas are very good to
>> have for anything that has variable amount of items/keys/arguments.
>> > >
>> > > This is a classic example I use to show why JSON is a bad idea:
>> https://github.com/npm/npm/commit/20439b21e103f6c1e8dcf2938ebaffce394bf23d#diff-6
>> > >
>> > > I believe the same thing applies for javascript functions. If it was
>> a bug in javascript, I wish for more such bugs really...
>> > >
>> > > 04.07.2014, 20:33, "Oliver Hunt" <oliver at apple.com>:
>> > >>  On Jul 3, 2014, at 3:52 PM, Dmitry Soshnikov <
>> dmitry.soshnikov at gmail.com> wrote:
>> > >>>   Hi,
>> > >>>
>> > >>>   Will it makes sense to standardize a trailing comma for function
>> arguments, and call parameters?
>>
>> 2. Function statements usually don't have such long lists of arguments
>> that such a thing would truly become useful. That is rare even in C, where
>> you may have as many as 6 or 7 arguments for one function.
>>
>
> Yes, it's true, however, my use-case was based on 80-cols rule we use in
> our code-base. And with type annotations (especially type annotations with
> generics, when you have types like `Map<string, IParamDefinition> $params`,
> etc) it can quickly become more than 80 cols, and our style-guide is to use
> each parameter on its own line, with a trailing comma for convenience of
> future adding that will preserve git blame logs if one doesn't  need always
> append the comma on previous line, in case when adding a new parameter.
>
> But again, I already think that for the language itself, it won't be super
> useful just yet, since backward-incompatible syntax won't allow using it
> anyways for a long amount of time, and not everyone has the build/transform
> step, that allows adopt this for older versions. That's said, a local
> extension seems the way to go for me.
>
>
Just received another the same question from developers: why don't we have
trailing commas for function arguments, it's so convenient using them with
arrays and objects, why not arguments?

So after rethinking it again -- will it still be interesting for ES7? (in
this case implementing own extension will already be supported by a future
standard).

Dmitry
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