Understanding "Prototypes" in JavaScript

Re:Understanding "Prototypes" in JavaScript by Cushman on Sunday August 14, 2011 @01:36PM (#2884033)

Here's the part I don't get: `Object.create`, as it's defined there, is a long-winded, roundabout way of saying

    {__proto__: o}

People seem to think that this is functionality that was lacking from JavaScript; many of these same people have some inexplicable distaste for the (non-standard) `__proto__` property. What gives?

(Okay, technically it's {__proto__: o, constructor: function F() {}}...)

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Re:Understanding "Prototypes" in JavaScript by alunny on Sunday August 14, 2011 @02:40PM (#2884148)

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/[email protected]/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...

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Re:Understanding "Prototypes" in JavaScript by Cushman on Sunday August 14, 2011 @09:21PM (#2885040)

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.

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