Return value of forEach

[Eric Devine]

Array#map does the non-trivial operation of copying the entire array. In
the example for loging to the console, this behavior is unintended. Perhaps
an underscore-like tap method should be considered to be added to the Array
prototype for these cases.

On Fri, Oct 16, 2015 at 9:32 AM, Andrea Giammarchi <
andrea.giammarchi at gmail.com> wrote:

> Like I've written before, if you need to return an array you can use map
> instead of forEach
>
> `arr.map(x => console.log(x) || x)`
>
> forEach has been like this since ever so while you wonder what kind of
> code would look like based on the fact forEach doesn't return  anything, I
> actually wonder how come there are still people expecting forEach to return
> something.
>
> So, it would be a breaking change and actually it's not needed since you
> have map.
>
> If the new Array, and for debugging purpose, is not desired, use `var log
> = DEBUG ? x => console.log(x) || x : x => x` and abuse it as much as you
> like.
>
> Would any of this work?
>
> Regards
>
>
>
> On Fri, Oct 16, 2015 at 2:23 PM, Niloy Mondal <niloy.mondal84 at gmail.com>
> wrote:
>
>> > That'd be a compatibility break.
>>
>> Ugh... you mean people actually depend on `forEach` returning `undefined`
>> (which it always does) to do further task?
>>
>> I wonder what that kinda code would look like >.<
>>
>> On Fri, Oct 16, 2015 at 6:08 PM, Frankie Bagnardi <f.bagnardi at gmail.com>
>> wrote:
>>
>>> That'd be a compatibility break.
>>>
>>> If we end up getting :: though:
>>>
>>> ```js
>>> function logEach(){
>>>   this.forEach((x) => console.log(x));
>>>   return this;
>>> }
>>>
>>>
>>> const a = [1, 2, 3]
>>>   .map(square)
>>>   ::logEach()
>>>   .map(plus1)
>>>   .reduce(add);
>>> ```
>>>
>>> You could make that a global variable so you can sprinkle it around your
>>> code in development.
>>>
>>> Having some developer tools in the language would be nice though. I
>>> don't even think console.log is in the spec. A global like Debug.logThis
>>> for example would be a more general ::-able.
>>>
>>>
>>> On Fri, Oct 16, 2015 at 5:32 AM, Andrea Giammarchi <
>>> andrea.giammarchi at gmail.com> wrote:
>>>
>>>> ```js
>>>> const a = [1, 2, 3]
>>>>   .map(square)
>>>>   .map(x => console.log(x) || x )
>>>>   .map(plus1)
>>>>   .reduce(add);
>>>> ```
>>>>
>>>> Regards
>>>>
>>>>
>>>> On Fri, Oct 16, 2015 at 10:13 AM, Niloy Mondal <
>>>> niloy.mondal84 at gmail.com> wrote:
>>>>
>>>>> Currently, `Array.prototype.forEach` returns `undefined`. It would be
>>>>> more
>>>>> useful if it returns the array itself.
>>>>>
>>>>> Say I have written some code like this...
>>>>>
>>>>> ```js
>>>>> const a = [1, 2, 3]
>>>>>   .map(square)
>>>>>   .map(plus1)
>>>>>   .reduce(add);
>>>>> ```
>>>>>
>>>>> For some reason, I am not getting the expected output. For debugging,
>>>>> I would
>>>>> like the print the values after each step. My first initial reaction
>>>>> is to
>>>>> put a `forEach` step in between and print the values like so...
>>>>>
>>>>> ```js
>>>>> const a = [1, 2, 3]
>>>>>   .map(square)
>>>>>   .forEach(x => console.log(x))
>>>>>   .map(plus1)
>>>>>   .reduce(add);
>>>>> ```
>>>>>
>>>>> Unfortunately, this does not work as `forEach` returns `undefined`. I
>>>>> now have
>>>>> to comment out all the code below it. Having the _plug and play_
>>>>> behaviour for
>>>>> `forEach` would be very convenient.
>>>>>
>>>>> _______________________________________________
>>>>> es-discuss mailing list
>>>>> es-discuss at mozilla.org
>>>>> https://mail.mozilla.org/listinfo/es-discuss
>>>>>
>>>>>
>>>>
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>>>>
>>>>
>>>
>>
>
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