summary element (child of detail)

[danielweck]

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/summary

summary should be added to the list:
https://github.com/davidtheclark/tabbable/blob/c5ad06c85e596fea038c8a59a97324627eaa2784/index.js#L1-L11

[davidtheclark]

Thanks, @danielweck. According to https://allyjs.io/data-tables/focusable.html, the summary element is not consistently tabbable across supported browsers. In 41f0000 I added it to the list of elements in that situation. You could add a tabindex to your summary elements to ensure they behave consistently, and are recognized by this library.

[danielweck]

Very useful response, thank you. However, in our use-case we side-load arbitrary HTML documents, and we avoid as much as possible interfering with the authored markup. We also have the luxury of controlling what browser engine is used, so we can make reliable predictions about the level of support for specific features (like the focusability / tab-ability of detail/summary elements). So, I will probably just fork your code and continue from there. Thank you! :)

[davidtheclark]

Ok, @danielweck 👍

Another possibility could be to add an option to this library that allows you to add selectors to the list — so in situations like yours you could add more elements.

[danielweck]

I recently revisited medialize/a11y.
Still unmaintained.
Also, relies on browser sniffing to address platform-specifc edge cases (not a bad thing per-se, just makes code hard to read + maintain):

https://github.com/medialize/ally.js/blob/master/src/is/tabbable.js

Equivalent of tabbable:

https://github.com/medialize/ally.js/blob/master/src/query/tabsequence.js

[danielweck]

I noticed that focusableAreas() in the W3C working draft of 'spatial' navigation (not 'sequential' nav) is "at risk".
https://www.w3.org/TR/css-nav-1/

I wonder if the focus / tab heuristics described in the documentation of medialize/a11y match those that the W3C group have been using to design the specification. Perhaps this bit is in fact underspecified, which is why the feature is marked 'at risk'.