[EuiButtonGroupButton] Make isSelected prop optional

[acstll]

Summary

EuiButtonGroup is currently meant "for indicating selection only" (docs). But button groups could be used to handle independent intent (clicks), as in toolbars e.g. upload a file.

Important

This PR does not affect EuiButtonGroup, only the internal EuiButtonGroupButton.

The PR makes the isSelected prop optional, so that the aria-pressed attribute is not always present as to indicate selection. Allowing different usages of buttons within button groups.

Why are we making this change?

To enable other usages for EuiButtonGroupButton other than selection.

Needed to improve accessibility in #9151.

Impact to users

🟢 No impact, internal change.

QA

• Ensure EuiButtonGroup is not affected and works as before.

Remove or strikethrough items that do not apply to your PR.

General checklist

• Browser QA
  • Checked in both light and dark modes
  • Checked in both MacOS and Windows high contrast modes
    • (emulate forced colors if you do not have access to a Windows machine.)
  • Checked in mobile
  • Checked in Chrome, Safari, Edge, and Firefox
  • Checked for accessibility including keyboard-only and screenreader modes
• Docs site QA
  • Added documentation
  • Props have proper autodocs (using @default if default values are missing) and playground toggles
  • Checked Code Sandbox works for any docs examples
• Code quality checklist
  • Added or updated jest and cypress tests
  • Updated visual regression tests
• Release checklist
  • A changelog entry exists and is marked appropriately
  • If applicable, added the breaking change issue label (and filled out the breaking change checklist)
  • If the changes unblock an issue in a different repo, smoke tested carefully (see Testing EUI features in Kibana ahead of time)
• Designer checklist
  • If applicable, file an issue to update EUI's Figma library with any corresponding UI changes. (This is an internal repo, if you are external to Elastic, ask a maintainer to submit this request)

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 47ea284
• Documentation website
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History

• 💚 Build #1774 succeeded ea1fdde

cc @acstll

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 47ea284

History

• 💚 Build #5095 succeeded ea1fdde

cc @acstll

[weronikaolejniczak]

Given that EuiButtonGroup is already passing a boolean and EuiButtonGroupButton now supports both standard and toggle behavior, the changes are correct 👍🏻

I verified that EuiButtonGroup works as expected:

	Before	After
Windows + Edge + NVDA	Kapture.2025-11-03.at.12.07.52.mp4	Kapture.2025-11-03.at.12.09.02.mp4
MacOS + Safari + VoiceOver	Kapture.2025-11-03.at.12.32.28.mp4	Kapture.2025-11-03.at.12.33.50.mp4

I also went ahead and used EuiButtonGroupButton as a regular button without isSelected and can verify aria-pressed is not present:

Thanks for the improvement, Arturo! 🙏🏻 🟢

Note: In the case were a component relied on EuiButtonGroupButton providing the false default, there could be an a11y regression. aria-pressed will work only if it's a boolean value, otherwise the screen reader gets confused and doesn't pronounce undefined as an "off" state of the toggle button. BUT EuiButtonGroupButton is only used internally in EuiButtonGroup and EuiFilterGroup and it works well.

[acstll]

@weronikaolejniczak thanks for taking the time to do the testing, much appreciated!