Are function arguments with the value `undefined` "present"?
bruant.d at gmail.com
Fri May 31 07:23:03 PDT 2013
I believe Boris Zbarski touched on this recently at
(I haven't read the full thread, so can't tell what the conclusion were,
but it's probably worth checking out)
Le 31/05/2013 04:33, Till Schneidereit a écrit :
> I couldn't find any precise definition for the spec term "present", so
> this is not entirely clear to me.
> In step 7 of 126.96.36.199 Array.prototype.reduce, a TypeError must be
> thrown if the optional argument `initialValue` isn't present. If a
> value of `undefined` does *not* cause the argument to be present, that
> function can be implemented with the following signature:
> `function ArrayReduce(callbackfn, initialValue = undefined)`
> If, however, the value `undefined` means that the argument is present,
> the signature should probably be:
> `function ArrayReduce(callbackfn, ...rest)`
> The question isn't entirely academic, as I'm trying to get the
> self-hosted implementations of builtins in SpiderMonkey to be as close
> to the spec as possible.
> es-discuss mailing list
> es-discuss at mozilla.org
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