Suggestion: Array.prototype.repeat

Rick Waldron waldron.rick at gmail.com
Tue Jan 3 06:10:33 PST 2012


On Tue, Jan 3, 2012 at 3:34 AM, Mariusz Nowak <
medikoo+mozilla.org at medikoo.com> wrote:

>
>
> Rick Waldron wrote:
> >
> > On Mon, Jan 2, 2012 at 3:56 PM, Mariusz Nowak <
> > medikoo+mozilla.org at medikoo.com> wrote:
> >
> >>
> >> I like it, it indeed looks very logical, however it's a bit
> controversial
> >> that we need to create temporary array object to get one that we want.
> >>
> >
> > Is the controversy editorial or fact, because the following methods are
> > all
> > specified to use a temporary, newly initialized Array internally:
> >
> > Array.prototype.concat
> > Array.prototype.filter (...)
> >
>
> Rick, you say that apart of output arrays this methods create some other
> temporary arrays internally ?
> I don't see anything like that in specification, where exactly is it stated
> ?
>


Array.prototype.concat
 - http://es5.github.com/#x15.4.4.4 #2

Array.prototype.filter
 - http://es5.github.com/#x15.4.4.20 #6

Array.prototype.map
 - http://es5.github.com/#x15.4.4.19 #6

Array.prototype.slice
 - http://es5.github.com/#x15.4.4.10 #2

Array.prototype.splice
 - http://es5.github.com/#x15.4.4.12 #2

String.prototype.match
 - http://es5.github.com/#x15.5.4.10 #8b

String.prototype.split
 - http://es5.github.com/#x15.5.4.14 #3

RegExp.prototype.exec
 - http://es5.github.com/#x15.10.6.2 #13

Object.getOwnPropertyNames
 - http://es5.github.com/#x15.2.3.4 #2

Object.keys
 - http://es5.github.com/#x15.2.3.14 #3





>
>
> > This doesn't produce the same as Array.prototype.repeat..
> >
> > // regular
> > console.log( Array.generate( 3, [1,2,3] ) );
> > // sparse
> > console.log( Array.generate( 3, [1,2,,3] ) );
> >
> > [ [ 1, 2, 3 ], [ 1, 2, 3 ], [ 1, 2, 3 ] ]
> > [ [ 1, 2, , 3 ], [ 1, 2, , 3 ], [ 1, 2, , 3 ] ]
> >
>
> It is supposed to be used that way:
> Array.generate(4, 1, 2, 3) // -> [1, 2, 3, 1];
>

Got it, I misunderstood, as there was no example usage - thanks for
clarifying.

Rick


>
> Usage you suggested as with Array.prototype.repeat will imply need of
> creating temporary array object.
>
> --
> Mariusz Nowak
> https://github.com/medikoo
>
>
> -----
> Mariusz Nowak
>
> https://github.com/medikoo
> --
> View this message in context:
> http://old.nabble.com/Suggestion%3A-Array.prototype.repeat-tp33067649p33070367.html
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>
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