571390 - classList is always empty on xul elements

Status: RESOLVED FIXED

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

Description

[Ian Neal]

Steps to reproduce
1/ Create some xul containing various elements with classes.
2/ Add some JS that uses classList property and associated methods to manipulate the elements' classes.

Expected result
1/ classList contains DOMTokenList of classes and associated methods can be used to manipulate the list.

Actual result
1/ classList is empty, so using add method overwrites anything in className property.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

The problem seems to be that DOMTokenList uses GetParsedAttr, but it should
probably use GetAttrInfo, which can handle XULprototypes.

Comment 2

[Ian Neal]

Say you have an xul element which has a class bar.
The DOMTokenList is empty at this point and className is "bar"
If you set the element's className to "foo" then the DOMTokenList gets populated.

Comment 3

[Boris Zbarsky [:bzbarsky]]

Right; see comment 1.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Attachment: patch

Comment 5

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 450646 [details] [diff] [review]
patch

This looks ok, but we should add a comment to the GetParsedAttr footgun.

Comment 6

[Olli Pettay [:smaug][[e-mail]]]

http://hg.mozilla.org/mozilla-central/rev/1d5faa6f718e
http://hg.mozilla.org/mozilla-central/rev/5ea4bc6c71f7