Reflect.hasOwn() ?

Boris Zbarsky bzbarsky at MIT.EDU
Sat Jul 26 19:17:31 PDT 2014


On 7/26/14, 5:33 AM, Tom Van Cutsem wrote:
> The rationale to remove Reflect.hasOwn was that it could easily be
> simulated via (Reflect.getOwnPropertyDescriptor(obj,name) !==
> undefined). While this conses a throw-away property descriptor object,
> the overhead was deemed insignificant.

That depends on how much work an implementation has to perform to 
produce the value of a value property, doesn't it.

In the case of some DOM objects that work can be fairly significant 
(e.g. O(N) in size of the document).

On the other hand, maybe performance of Reflect.* is just not that critical.

-Boris


More information about the es-discuss mailing list