Should aria-valuenow be required if aria-valuetext is used?

[scottaohara]

Happened across this issue in axe-core today - https://github.com/dequelabs/axe-core/issues/4515, and I think it raises a good question. Is there a good reason (for a user) for an author to need to maintain both an aria-valuenow and an aria-valuetext?

take for instance the youtube video scrubber:

<div class="ytp-progress-bar" tabindex="0" role="slider" 
  aria-label="Seek slider" aria-valuemin="0" aria-valuemax="30" aria-valuenow="13" 
  aria-valuetext="0 Minutes 13 Seconds of 0 Minutes 30 Seconds" style="">

if one were to remove the aria-valuenow, from my quick testing with Narrator, VoiceOver (macos/ios), NVDA and JAWS, there was no negative user impact to understanding the slider since the aria-valuetext was still being conveyed.

the visual styling of the indicator for sliders, progressbars, etc., are often not even based on the value of aria-valuenow

so largely this seems like it might just be 'extra work' for developers if they're using aria-valuetext, but still being required to declare an aria-valuenow which doesn't get exposed to users, and is not often the source of the visual styling for the slider/progressbar/etc. indicator.

But, maybe i'm missing something and this attribute still can be accessed and has value to users I'm not thinking about???

I'm less concerned about if authors might have use for it - cause if they do, great. Keep using it. This issue is just focused on determining why it needs to be an author requirement to specify the attribute if an author doesn't need it / it isn't being exposed to users anyway?