Symbols, Protocols, Frames, and Versioning

David Bruant bruant.d at
Fri Oct 5 09:48:33 PDT 2012

Le 05/10/2012 17:23, Mark S. Miller a écrit :
> On Fri, Oct 5, 2012 at 7:11 AM, Sam Tobin-Hochstadt <samth at
> <mailto:samth at>> wrote:
>     Note also that `Symbol.for` has some really weird behavior. For
>     example, what does this evaluate to?
>         Symbol.for("x") instanceof Symbol
>     That depends if someone has previously evaluated `Symbol.for("x")` in
>     a different frame.
> If this is true, then it is obviously a fatal problem with the whole
> proposal, independent of all other issues. Do symbols have a
> [[Prototype]] whose value is a Symbol.prototype?
Or more "profoundly", are symbols Objects (in the ES5.1 - 8.6 section
sense) at all or just lightweigh representations of object identities?

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