[alunny]

As I understand it, the main objection to `__proto__` is that it's writable, and thus not atomic with object creation. This creates a bunch of headaches for implementors for performance and security.

More knowledgable people than myself discuss it on this es-discuss thread: http://www.mail-archive.com/[e-mail]/msg06142....

There is a Harmony proposal for a "set prototype of operator" that would solve this problem; instead of writing:

    var newObj = {__proto__: OldObject, id: 5}

You would write:

    var newObj = OldObject <| { id: 5 }

Detailed here: http://wiki.ecmascript.org/doku.php?id=harmony:proto_operato...

[Cushman]

Yeah, I can understand how it makes implementors' lives easier... I just like it when they deal with annoying stuff so that I don't have to :)

I know people don't use mutable __proto__ for anything useful, but it does enable some neat tricks. Personally I wish implementors would embrace it and optimize for it rather than trying to make it go away.

As for the "prototype for" operator... that's disgusting.