On Mon, Nov 11, 2013 at 9:21 AM, Allen Wirfs-Brock
<allen at wirfs-brock.com> wrote:
> On Nov 11, 2013, at 6:10 AM, Mark S. Miller wrote:
>> On Sun, Nov 10, 2013 at 11:33 PM, Corey Frang <gnarf37 at gmail.com> wrote:
>>> Just to provide another way of working around it:
>>>
>>> var empty = {}; // or even a symbol?
>>>
>>> function splice(start = empty, count = 0, ...items) {
>>> if (start === empty) { ...
>>> }
>>
>> That is excellent! Has all the upsides of the best of the other proposals
>> and none of the downsides.
>
> No, this doesn't work because then both
> [1,2,3].splice()
> [1.2.3].splice(undefined)
>
> will both result in start === empty. But for web compatibility they must be
> treated differently.
Right. The one and only way to test for missing args different from
undefined is to use a rest arg and test length, as demonstrated
earlier in this thread.
~TJ
domenic at domenicdenicola.com (2013-11-15T18:54:39.241Z)
Right. The one and only way to test for missing args different from
undefined is to use a rest arg and test length, as demonstrated
earlier in this thread.
On Mon, Nov 11, 2013 at 9:21 AM, Allen Wirfs-Brock <allen at wirfs-brock.com> wrote: > On Nov 11, 2013, at 6:10 AM, Mark S. Miller wrote: >> On Sun, Nov 10, 2013 at 11:33 PM, Corey Frang <gnarf37 at gmail.com> wrote: >>> Just to provide another way of working around it: >>> >>> var empty = {}; // or even a symbol? >>> >>> function splice(start = empty, count = 0, ...items) { >>> if (start === empty) { ... >>> } >> >> That is excellent! Has all the upsides of the best of the other proposals >> and none of the downsides. > > No, this doesn't work because then both > [1,2,3].splice() > [1.2.3].splice(undefined) > > will both result in start === empty. But for web compatibility they must be > treated differently. Right. The one and only way to test for missing args different from undefined is to use a rest arg and test length, as demonstrated earlier in this thread. ~TJ