Add a container-field to NavigationEvent

[hugoholgersson]

Let's add a container-attribute to NavigationEvent?

It will default to document.body unless spatnav-container imposed a restriction on the search.

When dispatching the event, the browser has this information at hand already, so why not share this possibly important piece of information to authors?

[frivoal]

In navnotarget and navbeforescroll※ it is included already in relatedTarget.

What would you suggest we put in relatedTarget for navnotarget and navbeforescroll if there was a separate container attribute? The same information? null?

※ In the case of navbeforescroll, relatedTarget is described as the thing you scroll, but that's a spatnav container anyway, so it's just a matter of how you look at it. The info is there.

It will default to document.body unless spatnav-container imposed a restriction on the search.

Or unless there's a scroller in the ancestry chain, since this create spatnav containers as well.

[hugoholgersson]

I didn't think of that. But I realized, I think nextFocus is a better name than relatedTarget, see #34.

What would you suggest we put in relatedTarget for navnotarget and navbeforescroll if there was a separate container attribute? The same information? null?

Yes, maybe null is fine? That's a hint that nothing will be focused?

It will default to document.body unless spatnav-container imposed a restriction on the search.
Or unless there's a scroller in the ancestry chain, since this create spatnav containers as well.

Right. Good point. Scrollers that "jail" the focused element would be reported in container as well. Chromium's current spatnav algorithm happily exits scrollers, so today scrollers don't impose any restrictions. This is something I'd like to see fixed by first focusing the scroller.

[hugoholgersson]

Finding the parent scroller, i.e. the element's "container", can be done in standard JS [1] [2].