Bug 33946 – Object.getOwnPropertyDescriptor always returns undefined for JS API objects

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Kent Hansen]

When Object.getOwnPropertyDescriptor is passed an object that was created using the C API JSObjectMake() function, it doesn't return a valid property descriptor, even if the property is defined in the JSClass.

[Kent Hansen]

Created attachment 47125 [details]
Proposed patch

Implements the approach suggested by Geoffrey in https://bugs.webkit.org/show_bug.cgi?id=33603#c11.
Descriptors always have enumerable=false, even though that might not be true. It's no worse than before, since Object.prototype.propertyIsEnumerable would also return false (since it calls getOwnPropertyDescriptor(), which wasn't implemented). Like I mention in a comment, it can be made more consistent by calling getPropertyNames and checking if the name is in the result, but I've opted not to add that overhead unless it's requested.
In a full-blown solution (using access descriptors), the implementation would extract the attributes from the JSStaticValues/JSStaticFunctions if possible, but it doesn't look like the functionality can be completely supported without introducing a new callback in JSClassDefinition (i.e., to get attributes of non-static properties).

[Geoffrey Garen]

Comment on attachment 47125 [details]
Proposed patch

Nice.

r=me

[WebKit Commit Bot]

Comment on attachment 47125 [details]
Proposed patch

Clearing flags on attachment: 47125

Committed r53638: <http://trac.webkit.org/changeset/53638>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.