Bug 53752 – [JSC binding] Inconsistent behavior of DOMStringMap

• Status: RESOLVED
• Resolution: FIXED
• Component: DOM

[Kent Tamura]

The behavior of the current JSC binding for DOMStringMap is:
  put: Handle JavaScript property first, then handle HTML attribute if there is not JS property.
  delete: ditto.
  get: Handle HTML attribute, then handle JavaScript property.

The get operation is inconsistent with put/delete.  So, we have the following curious behavior:

1> document.body.dataset.toString
function toString() { ...
2> document.body.setAttribute('data-to-string', 'attr')
3> document.body.dataset.toString
  "attr"
4> document.body.dataset.toString = function() { return "dataset"; }
5> document.body.dataset.toString
  "attr"

Even if one sets a new value to .toString [4], .toString doesn't return the new value [5].  It's not good.

I think it's reasonable to handle JavaScript properties first to protect JavaScript Object behavior.  However, we should do it in the get operation too and should give up providing "data-to-string" attribute via HTMLElement::dataset for consistency.

[Kent Tamura]

Created attachment 81440 [details]
Incomplete patch

The last test (delete div.dataset.foobarbaz) doesn't work.

[Kent Tamura]

(In reply to comment #0)
> I think it's reasonable to handle JavaScript properties first to protect JavaScript Object behavior.  However, we should do it in the get operation too and should give up providing "data-to-string" attribute via HTMLElement::dataset for consistency.

I changed my mind. Both of Firefox and Opera always handles data-* attributes first.  We had better follow them.

[Kent Tamura]

Created attachment 109933 [details]
Patch

[Darin Adler]

Comment on attachment 109933 [details]
Patch

Looks good.

[Kent Tamura]

Comment on attachment 109933 [details]
Patch

Thank you for reviewing.

[WebKit Review Bot]

Comment on attachment 109933 [details]
Patch

Clearing flags on attachment: 109933

Committed r96893: <http://trac.webkit.org/changeset/96893>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.

[Kent Tamura]

A follow-up test change: http://trac.webkit.org/changeset/96911