Is the attribute aria-level on role=grid and role=tablist necessary?

[spectranaut]

What are the use cases for aria-level on role=grid and role=tablist? If there is no use cases, is it a bug that ARIA allows this?

aria-level on role=grid

Nested grids are possible to imagine on a website, but it seems hard to imagine that nest grids would not also be nested in the DOM. And if it is nested in a DOM, shouldn't the user agent calculate this information?

aria-level on role=tablist

See the description of aria-level for use on the role=treeitem:

"This attribute is applied to elements that act as leaf nodes within the orientation of the set, for example, on elements with role treeitem rather than elements with role group. This means that multiple elements in a set may have the same value for this attribute. Although it would be less repetitive to provide a single value on the container, restricting this to leaf nodes ensures that there is a single way for assistive technologies to use the attribute."

And the description of aria-level on role=row:

"In the case of a treegrid, aria-level is supported on elements with the role row, not elements with role gridcell. At first glance, this may seem inconsistent with the application of aria-level on treeitem elements, but it is consistent in that the row acts as the leaf node within the vertical orientation of the grid, whereas the gridcell is a leaf node within the horizontal orientation of each row. Level is not supported on sets of cells within rows, so the aria-level attribute is applied to the element with the role row."

It seems like aria-level should be on role=tab according to this logic.

cc @zcorpan @mcking65

[zcorpan]

It looks like this issue was mentioned in https://www.w3.org/2019/03/21-aria-minutes.html

mck: I want to put a discussion of this on the agenda relatively soon
jamesn: I'll put 1.2 on it

@mcking65 @jnurthen has this issue been discussed after that?

[jnurthen]

IMO tablist sounds correct - I've come across nested tablists in applications a number of times. If AT were to support this it would be helpful IMO. @curtbellew and @stes-acc probably have a bunch of use cases.

I can't see a use case for grid right now - anyone have one?

[mcking65]

@jnurthen, while I am not opposed to leaving aria-level on tablist, it is difficult to imagine how this would be utilized by screen readers. Perhaps the screen reader might look up the tree to find out that a tab is a level 2 tab. If it did, I don't really know how the screen reader could help the user with that information. In some situations, depending on where the nested tabs fall within the parent tabpanel, the information may be entirely useless to the user.

In other words, to me, the utility of aria-level on tablist or tab seems more theoretical than utilitarian.

I believe there is zero utility on grids and that we could consider removing it.

[zcorpan]

@jnurthen Can you show an example of an application with nested tablists? I suppose the nested tablist would be inside the tabpanel?

[a11ydoer]

@mcking65 is seeking the input regarding what the best strategy for addressing the use cases which are not happening often, so called "edge cases"

[jnurthen]

@curtbellew I know there are products which used to have this - can you comment if you need this support to remain. Honestly I'd be in favour of removing the support but I know there are UIs which do this.

[a11ydoer]

@jnurthen are you talking about aria role either "grid" or "tablist" above?

[jnurthen]

@a11ydoer tablist - I can't think of a reason to have a level on grid.

[smhigley]

Going back through old emails, I found one example of role="group" within a tablist. It was a vertically-oriented set of tabs that controlled the content of a panel (which was also the principal content for the app). The tabs were hierarchical -- a bit like a tree but without expand/collapse capability.

I think it could be argued that it should have been a tree, and that perhaps it should have supported expand/collapse to benefit high zoom and smaller screens.

Even with that example, I believe I agree with @jnurthen in favor of removing it, at least until enough different people come forward with valid use cases for it that aren't better served by a different pattern.

[curtbellew]

@jnurthen Unfortunately I can't point to a specific use case in the wild here. I only have fuzzy memories of tablists using aria-level. I've got a couple emails out internally asking for access to environments I can look at but at this point I don't have anything from the real world.

[scottaohara]

#1029 removed aria-level from grid so that part of this issue has been resolved.

I made #1079 to either be accepted to remove the attribute from tablist, or to be rejected. In either case, the outcome of the PR will close this issue.