Why doesn't Array.from() pass the array to the mapFn?

T.J. Crowder tj.crowder at farsightsoftware.com
Wed May 3 11:46:20 UTC 2017

On Wed, May 3, 2017 at 12:39 PM, the kojoman <kojoman at gmail.com> wrote:

> Thanks for the clarification. I thought the mapping was applied
> afterwards.
> I would still argue that it would be better to skip it all together than
> having it and not working like the existing map function.
So Array.from(array-like).map(mapFn) is the way to go then?

Why make two passes over the contents rather than just one?

It is interesting that `Array.from` doesn't pass its first parameter
(`items`, the source object) as the third argument to the mapping function.
I suspect it's because the index doesn't necessarily work with the source
object, if an iterator is being used...

-- T.J. Crowder
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