On 10/1/2012 6:43 PM, Brendan Eich wrote:
Nicholas C. Zakas wrote:
I've been playing around with the Set prototypes in Firefox and
Chrome (knowing full well that they are incomplete and the spec
hasn't been finalized yet), and I wanted to share a couple of learnings.
Thanks!
First, since a Set can be initialized with an array, it stands to
reason that you should be able to easily get an array back from the
set. However, there is no way to do that right now short of using a
loop and manually constructing an array. I would really like to see a
*Set.prototype.toArray* method to easily change the Set back into an
array. A simple use case would be de-duping an array:
function dedupe(array) {
return (new Set(array)).toArray();
}
Array.from is the way we hope to avoid burdening many iterables with
"toArray" methods, as Rick pointed out. Ok?
Better than okay, that's great. Having one way to convert iterables to
an array makes a lot of sense to me.
Second, the lack of visibility into Sets is problematic. A very
simple use case is when I want to see if the Set has been initialized
yet but I can't know what keys might have been used at that point in
time. Firefox implements a *Set.prototype.size* method which is
useful to know what I'm dealing with. However, I'm not sure how
frequently the number of items in the Set actually matters, so a
*Set.prototype.isEmpty* would be equally useful for this case.
+1 on isEmpty().
:D
Otherwise, I'm finding Sets very useful as a replacement for objects
that I was using for the same purpose.
Cool. Have you tried Maps for those cases where you want value ->
value mappings?
Not yet, that's next on my list.
/be
--
___________________________
Nicholas C. Zakas
http://www.nczonline.net
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