On Fri, May 31, 2013 at 5:01 PM, Rick Waldron <[email protected]>wrote:
> `undefined` is a valid initial value for Array.prototype.reduce. > `undefined` will also trigger the default parameter, so this works until > nothing is provided, which breaks Step 10. > I guess that's what my question boils down to: is `undefined` a valid initial value? It probably has to be for backwards-compatibility reasons. > > >> >> If, however, the value `undefined` means that the argument is present, >> the signature should probably be: >> >> `function ArrayReduce(callbackfn, ...rest)` >> > > With minor changes to steps 9 and 10, plus the addition of steps to check > rest.length and then Get(rest, "0"), this would work. I suspect that Allen > would prefer to craft some sort of spec mechanism, from this use case, for > "is foo present" assertions throughout the spec. > That's what I'm using for the moment, and will probably continue using, given the abovementioned conclusion regarding backwards-compatibility, yes. thanks, till
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