856647 - Throw on Object.preventExtensions(document)

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[David Bruant]

From WebIDL:
http://dev.w3.org/2006/webapi/WebIDL/#indexed-and-named-properties
> Platform objects implementing an interface that supports indexed or
> named properties cannot be fixed; if Object.freeze, Object.seal or
> Object.preventExtensions is called on one of these objects,
> these the function MUST throw a TypeError.

Currently, Object.preventExtensions(document) doesn't throw while it should.
(thanks Ms2ger for the heads up)

Comment 1

[Boris Zbarsky [:bzbarsky]]

Presumably moving to WebIDL bindings here will fix.  Certainly it works right for nodelists.

Comment 2

[Boris Zbarsky [:bzbarsky]]

One spec question:  Should Object.preventExtensions(window) throw?  As spec is written right now, yes, but that doesn't seem right to me.

Comment 3

[Cameron McCormack (:heycam)]

If it doesn't throw, then you need to define what happens if new indexed properties are meant to appear on the object.  Having them appear when the object has [[Extensible]] == false would violate the rules for host objects in http://es5.github.com/#x8.6.2.  I thought it would be simpler to disallow this rather than define the set of visible indexed properties to be capped at what it is at the time Object.preventExtensions() is called.

Comment 4

[Boris Zbarsky [:bzbarsky]]

Ah, I had forgotten that indexed properties are on the object itself.  So yeah, throwing for a window makes sense, esp. as you're always talking about a WindowProxy anyway.

Comment 5

[:Ms2ger (he/him; ⌚ UTC+1/+2)]

Looks fixed here.