Non-extensibility of Typed Arrays

Oliver Hunt oliver at
Tue Aug 27 09:18:14 PDT 2013

The curent argument for non-extensibility seems to be mozilla doesn't support them.  It sounds like all other engines do.

There are plenty of reasons developers may want expandos - they're generally useful for holding different kinds of metadata.  By requiring a separate object to hold that information we're merely making a developer's life harder.  This is also inconsistent with all other magically-indexable types in ES and the DOM.

I'm also not sure what the performance gains of inextensibility are, if DH could expand it would be greatly appreciated.


On Aug 27, 2013, at 9:04 AM, Allen Wirfs-Brock <allen at> wrote:

> see meeting notes 
> On Aug 26, 2013, at 5:34 PM, Oliver Hunt wrote:
>> So I noticed in the last revision to the TA spec that a decision was made to prevent extensibility of them.  Can someone say why that decision was made? It makes TAs somewhat unique vs. all other builtin types and doesn't match the behavior of Blink or WebKit implementations.
>> While I am usually in favour of conservative behaviour I'd like more information on the reasoning behind this choice.
>> --Oliver
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>> es-discuss mailing list
>> es-discuss at

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