Add option labelId to improve a11y

[brosua]

Description

A new option labelId was introduced. If this option is set, the choices element contains aria-labeledby. If someone uses a screenreader, he/she will get information, which label is associated with the focused input.

This fixes #937.

Screenshots (if appropriate)

Types of changes

• Chore (tooling change or documentation change)
• Refactor (non-breaking change which maintains existing functionality)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[mtriff]

I haven't done a full review yet, but this seems great! Could we enable this by default if the choices element has an id? I'm not very familiar with using aria-labeledby in real world use cases, so I'm not sure if it's safe to make that assumption.

[brosua]

Hi @mtriff ,
yes, that is possible. The id of the passed element can be determined and used by aria-labeledby. The choices option would override this value (edge cases).

[mtriff]

@brosua, sorry for the delay. I just realized I never fully reviewed this. It looks good, I'd like to see the following before merging:

• Rebase on the latest version of master
• Add functionality to automatically set labelId if the passed element has an id attribute
• Add tests confirming that the labelId is automatically set, as well as the case where no id attribute is available

[brosua]

Hi @mtriff , I thought about your idea again.
We can´t set the labelId automatically. This is the id of the label. I doubt, that trying to identify the correct label to read the id, is a good idea.

[mtriff]

That makes sense to me. This needs a unit test where labelId is set to something before merging.

[brosua]

Hi @mtriff
test case is added.

[mtriff]

Wonderful, thanks for the contribution!