<dialog> Unclear method of altering/reading attributes

[jakearchibald]

https://html.spec.whatwg.org/multipage/interactive-elements.html#dom-dialog-show

Add an open attribute to the dialog element, whose value is the empty string.

The spec is unclear how this attribute is added. It should use https://dom.spec.whatwg.org/#concept-element-attributes-set-value, unless that isn't how the attribute should be added.

Other instances that should be linked:

Add an open attribute to subject, whose value is the empty string.

If the element already has an open attribute, then return.

If subject already has an open attribute, then throw an "InvalidStateError" DOMException.

Add an open attribute to subject, whose value is the empty string.

If isModal is true and subject has the autofocus attribute, then set control to subject.

If subject does not have an open attribute, then return.

Remove subject's open attribute.

If result is not null, then set the returnValue attribute to result.

[domenic]

This isn't specific to dialog. Every time the HTML spec modifies attributes, it does so without linking to DOM. I suspect because most of it was written before DOM was.

Personally I think this is fine; I can't come up with any ambiguous reading. But if someone wants to fix this, that'd be nice!

[jakearchibald]

The ambiguity I see is in adding an attribute of a given name to an element that already has an attribute of that name.

I guess the intent is to 'set' rather than 'add'.

Other options would be to fail, or do what el.append() does, and remove the attribute node, and replace it with a new node, which changes equality and ordering of attribute nodes.