[cursor]

Button active state listened for the deprecated keypress event. In the repository-pinned Chromium, preventing default on keypress does not cancel the space-bar scroll that already starts on keydown. StateActiveController now uses keydown, which keeps the active state and stops that scroll.

Removed mechanism

projects/forms/src/internal/controllers/state-active.controller.ts added and removed a keypress listener for keyboard activation. That listener is now keydown.

Native replacement and benefit

keydown is the event that carries the space-bar scroll default action. Calling preventDefault() there cancels the scroll. The same call on keypress is too late.

Measured in Playwright 1.64.1, Chromium revision 1248, runtime 156.0.8078.4, on 2026-11-14 (viewport 600×300, page height 2000px, focusable host, Space held about 80ms):

• no preventDefault: scrollTop 142
• preventDefault on keypress: scrollTop 72
• preventDefault on keydown: scrollTop 0, and the following keypress is suppressed

Compatibility sources

• MDN Element: keypress event (deprecated; use beforeinput or keydown)
• UI Events keypress
• Baseline keypress_event (api.Element.keypress_event)
• Chromium bug 40879837: Chrome does not fire keypress for known keyboard shortcuts; use keydown

Primary support remains Chrome, per projects/site/src/docs/about/support.md. Firefox and Safari both implement keydown. Firefox has not fired keypress for most non-printable keys since version 65 (Enter is the exception). No public entrypoint changes. The empty @nvidia-elements/core/polyfills export stays published.

Preserved behavior

• Space and Enter still set :state(active) until keyup, blur, or mouseup.
• Enter is not preventDefaulted. Space on the host is, including when the control is disabled.
• Click synthesis for Space and Enter stays on keyup in TypeSubmitController.
• Command and popover trigger handlers still listen for click. defaultPrevented on keydown does not cancel those clicks.
• A disabled host does not enter the active state.

Validation

• Playwright 1.64.1 Chromium revision 1248 (156.0.8078.4) scroll probe, 2026-11-14
• projects/forms: Prettier check, pnpm run lint, pnpm run test:types, and the unit suite (23 files, 298 tests), including a real Space and Enter active-state test
• Root mise exec -- pnpm run ci: exit 0

  

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[github-code-quality]

Code coverage overview

Languages: TypeScript

TypeScript / code-coverage/vitest

main 1417043	topic/web-modernizat... 61d9a98	+/-
99%	99%	0%

ℹ️ Calculations represent line coverage. Results may change as calculations are updated.

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_{Updated November 15, 2026 03:59 UTC}