Intent to Prototype: document.advanceFocus() and beforefocus
Marat Abdullin
Contact emails
Marat Abdullin mar...@microsoft.com
Explainer
https://open-ui.org/components/beforefocus.explainer
Specification
https://open-ui.org/components/beforefocus.explainer
This is an incubating design, not yet an adopted standard. Proposed HTML
integration: https://github.com/whatwg/html/issues/13104.
Summary
document.advanceFocus() lets
a page move focus using the browser's own Tab
order, with options for direction, starting point, containment and wrapping.
It returns a Promise reporting the outcome. The cancelable beforefocus event
lets a page stop a focus move before an element receives focus.
Blink component
Blink>HTML>Focus
Web Feature ID
Not assigned; requested in:
https://github.com/web-platform-dx/web-features/issues/4558.
Motivation
Dialogs, keyboard navigation and protection against focus theft often require
apps to reconstruct focus order or redirect focus after it has moved. These
primitives let apps use the browser's navigation instead, including across
shadow DOM and embedded frames.
Initial public proposal
https://github.com/openui/open-ui/issues/1261
Goals for experimentation
No origin trial is proposed. The current work is limited to off-by-default
prototyping and feedback on API ergonomics and safe focus interception.
Requires code in //chrome?
No. The current Chromium prototype does not change files under
//chrome.
Tracking bug
https://issues.chromium.org/issues/575489395
Measurement
The Blink WIP prototype adds
DocumentAdvanceFocus for
method calls and
BeforeFocusEvent for
browser-generated event dispatch.
Implementation: https://chromium-review.googlesource.com/c/chromium/src/+/8612302.
These are prototype use counters, not an assigned Web Feature ID.
Estimated milestones
None proposed; this is an off-by-default prototype, not a shipping request.
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5134711960764416?gate=5156755611975680
Prototype and related work
Chromium implementation: https://chromium-review.googlesource.com/8612302.
In a build containing the Chromium patch, enable
FocusNavigation with
--enable-blink-features=FocusNavigation;
pages also opt in with:
<metaname="focus-navigation"content="advanceFocus beforefocus">
The Chromium and Firefox prototypes have matching tentative WPTs,
supplemented by native tests.
Blink test review:
https://chromium-review.googlesource.com/c/chromium/src/+/8612302/2.
Gecko test review:
https://phabricator.services.mozilla.com/D335668?id=1414112.
These are browser-prototype review links, not a standalone upstream WPT PR.
A single upstream export remains to be coordinated.
Firefox tracking:
https://bugzilla.mozilla.org/show_bug.cgi?id=2084212.
Firefox intent: planned. I will reply here with the dev-platform thread once
it is public.
Firefox implementation: https://phabricator.services.mozilla.com/D335668.
I welcome feedback on API ergonomics and safe focus interception, particularly
keyboard and assistive-technology behavior. These are contributor-maintained
prototypes, not independent vendor endorsements. Current local testing is on
macOS, not all platforms.
This intent message uses the Chrome Platform Status generated template,
supplemented with prototype details.