Question regarding duplicate __proto__ properties
michalwadas at gmail.com
Sun Nov 30 10:35:50 PST 2014
Should it be possible to have property named "__proto__" which is
inaccessible in modern implementations?
30 lis 2014 18:53 "Allen Wirfs-Brock" <allen at wirfs-brock.com> napisał(a):
> On Nov 29, 2014, at 3:38 PM, Nicholas C. Zakas wrote:
> In Rev 28, B.3.1 it states:
> It is a Syntax Error if PropertyNameList of PropertyDefinitionList contains
> any duplicate entries for"__proto__" and at least two of those entries
> were obtained from productions of the formPropertyDefinition :
> PropertyName : AssignmentExpression .
> I noted that the duplicate name restriction was eliminated back in July
> and was just wondering if __proto__ is indeed a special case?
> Yes, `__proto__ : <expr>` in an object literal is a special form with
> different semantics than the other *PropertyDefinition* forms. The
> relaxation of the duplicate entry was explicitly not applied to it.
> It's worth noting that:
> __proto__: <expr>
> ["__proto__"] : <expr>
> do not mean the same thing.
> The first form does a [[SetPrototypeOf]] and is the form that the above
> early error applies to.
> The second form does a [[DefineProperty]] and does not place any
> restrictions of duplicates.
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> es-discuss at mozilla.org
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