Define dataset as a mixin for HTMLElement and SVGElement

[nikosandronikos]

The SVGElement and HTMLElement interfaces both define a dataset IDL attribute.

The SVGWG are wondering about the possibility of moving the definition into DOM as a mixin interface that can then be applied to both HTMLElement and SVGElement.

Issue in SVGWG tracker: w3c/svgwg#60

[annevk]

Maybe HTML would be a better place to provide this abstraction, since everything has to depend on HTML anyway?

[nikosandronikos]

If you think that's the appropriate place then that's ok with us. Where it ends up isn't as important as having only a single definition.

[annevk]

I think I would prefer that. We put class and id in DOM because they are "superglobal attributes". Features that are "global attributes" for a limited set of namespaces probably don't really belong in DOM directly, insofar we have any meaningful modularization here...

@domenic agreed?

[domenic]

Yeah I guess the reasoning in your last comment makes sense.

So in terms of HTML changes, I'm thinking, create a new ElementDataset mixin in the section #embedding-custom-non-visible-data-with-the-data-*-attributes, move [SameObject] readonly attribute DOMStringMap dataset; there, and then in the HTMLElement definition, add implements ElementDataset like we already have for implements ElementContentEditable.

[annevk]

Yeah, and we need to verify all attribute manipulation is generic enough. And maybe the data-* conformance should be made reusable or directly defined for SVG too.

[annevk]

See also https://bugzilla.mozilla.org/show_bug.cgi?id=921834. Apparently WebKit/Blink expose it directly on Element. Gecko plans to add it to SVGElement. Edge only has it on HTMLElement.

[domenic]

Apparently WebKit/Blink expose it directly on Element.

If you read a bit further down this is not true. Confirmation, at least in Blink (not near my WebKit computer): http://software.hixie.ch/utilities/js/live-dom-viewer/?saved=4371

[annevk]

Oops, my bad. Okay, maybe given that @cdumez can patch WebKit.

[cdumez]

@annevk: so moving dataset from Element to HTMLElement / SVGElement ?

[annevk]

@cdumez yes.

[cdumez]

@annevk Not a problem then: http://trac.webkit.org/changeset/204377

[cvrebert]

So that just leaves Edge: https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/10790130/

[dstorey]

Edge now supports this on SVGElement, along with a number of other things like tabIndex, focus(), blur().

They all seem like something that could be in a mixin.

[annevk]

I'm moving this to whatwg/html#3471 as this is really an issue with the HTML Standard.