B.3.1 The __proto__ pseudo property

Brendan Eich brendan at mozilla.com
Sun Apr 21 18:07:38 PDT 2013

Mark S. Miller wrote:
> For all parties, some examples of legacy uses of {__proto__: ....}, 
> whether hypothetical or observed, would help a lot. I doubt the stance 
> "special literal syntax for initializing [[Prototype]] without using 
> either [[Put]]/[[Set]] nor [[DefineOwnProperty]]" would be 
> incompatible with web reality.

It's possible we could make the change and nothing would break. Usually 
the burden of proof is on the people proposing the change, though (you 
and Allen).

If no implementation supports reconfiguration (delete or replacement) of 
Object.prototype.__proto__, then as you note, it can't yet matter and 
there's no observable compatibility break. But is there no such 


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