Question regarding duplicate __proto__ properties
# Allen Wirfs-Brock (10 years ago)
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>
and
["__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.
# Michał Wadas (10 years ago)
Should it be possible to have property named "__proto__" which is
inaccessible in modern implementations?
# Jeff Walden (10 years ago)
It's perfectly accessible.
var obj = { ["__proto__"]: 42, __proto__: null };
assert(obj.__proto__ === 42);
assert("__proto__" in obj);
assert(Reflect.get(obj, "__proto__") === 42); // ...if I remember R.get's name/semantics
assert(Object.getOwnPropertyDescriptor(obj, "__proto__").value === 42);
assert(Object.getPrototypeOf(obj) === null);
And so on.
In Rev 28, B.3.1 it states:
I noted that the duplicate name restriction was eliminated back in July1 and was just wondering if
__proto__is indeed a special case?In Rev 28, B.3.1 it states: * It is a Syntax Error ifPropertyNameListofPropertyDefinitionListcontains 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[1] and was just wondering if __proto__ is indeed a special case? Thanks. [1] https://github.com/rwaldron/tc39-notes/blob/46d2396e02fd73121b5985d5a0fafbcdbf9c9072/es6/2014-07/jul-29.md#41-review-latest-draft -- ___________________________ Nicholas C. Zakas http://www.nczonline.net -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20141129/4c74a447/attachment.html>