Must built-in prototypes also be valid instances? (Was: Why DataView.prototype object's [[Class]] is "Object"?)

Brendan Eich brendan at
Sat Sep 29 21:04:50 PDT 2012

Rick Waldron wrote:
> On Sat, Sep 29, 2012 at 6:19 PM, Brendan Eich <brendan at 
> <mailto:brendan at>> wrote:
>     Allen Wirfs-Brock wrote:
>         My intention, subject to feedback here and from TC39,  is to
>         follow the pattern I used for Map as much as possible.
>          However, TypedArray object are all ready implemented by all
>         major browsers to that may limit how we apply it to them.
>     Implementations differ:
>     javascript:alert(,-1))
>     in Opera says "Uint8Array", while in Firefox and Safari it says
>     "Uint8ArrayPrototype". Chrome says "Object". I can't test IE here.
> How common is that?

Which "that"?

> Generally the [[Class]] (NativeBrand?) is derived via
> (sans .prototype)


I'm saying typed arrays from khronos are underspecified, and 
implementations vary. Something to fix in ES6.


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