Array.isArray(new Proxy([], {})) should be false (Bug 1096753)

Allen Wirfs-Brock allen at wirfs-brock.com
Fri Nov 14 12:00:42 PST 2014


On Nov 14, 2014, at 11:41 AM, Domenic Denicola wrote:

> From: Allen Wirfs-Brock [mailto:allen at wirfs-brock.com] 
> 
>> What do you mean by "is an instance of some %ArrayPrototype%"? Do you mean that it has some %ArratPrototype% in it's prototype chain?
> 
> Yeah, more or less. A "realm-independent instanceof." This makes sense also from the historical perspective that `Array.isArray` was meant to provide a cross-realm alternative to `instanceof Array`. (I believe that was the case; before my time.)

No really, it was a way to expose a test of the [[Class]] internal property.  That test wasn't dependent upon the [[Prototype]] chain.

Allen



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