Non-extensibility of Typed Arrays

Brendan Eich brendan at
Tue Aug 27 09:39:28 PDT 2013

On Aug 27, 2013, at 9:35 AM, Oliver Hunt <oliver at> wrote:

> Existing types with magic index properties (other than Array) just drop numeric expandos on the floor so it's logically a no-op.  Unless there was a numeric accessor on the prototype (which non-extensibility does not save you from).

Those are a problem and an anti-use-case.

> My complaint is that this appears to be removing functionality that has been present in the majority of shipping TA implementations, assuming from LH's comment that Chakra supports expandos

Does anyone care, though?

TA instances having no indexed expandos but allowing named ones is weird. Better to be consistent to users and help implementations optimize further.


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