[Accessibility] Slider: Doesn't Announce Current Value

[HalcyonPride]

Environment Information

• Package version(s): Latest
• Browser and OS versions: Edge; Windows 10 Enterprise, version 1809

Please provide a reproduction of the bug in a codepen:

https://developer.microsoft.com/en-us/fabric#/components/slider

Actual behavior:

Narrator doesn't announce the current value as you move the slider.

Expected behavior:

Narrator should announce the current value.

Priorities and help requested:

Are you willing to submit a PR to fix? No

Requested priority: High

Products/sites affected: ODB

[JasonGore]

The same behavior also occurs with an ARIA slider example indicating that this is an issue with either Microsoft Edge or Narrator. I've also tested with NVDA, which announces the Slider value in Chrome, but not in Microsoft Edge. As a result, I suspect this is an issue with Microsoft Edge.

I'm working to create an issue with the Microsoft Edge team now.

[JasonGore]

Further investigation shows that this ARIA slider example works correctly. The primary difference appears to be the presence of the aria-valuetext value. when this value is missing, MS Edge/Narrator do not appear to fall back to aria-valuenow attribute for narration.

aria-valuetext is not specifically required by ARIA standards for narration, so this is still considered an issue with MS Edge & Narrator. Consumers of Slider can use the ariaValueText prop as a temporary workaround.

[HalcyonPride]

@JasonGore, I concur with your assessment. Since you're gonna open an issue with Edge, I'll close this Bug.