1990256 - Implement OpaqueRange

Status: ASSIGNED

(Core :: DOM: Forms, enhancement)

Description

[Stephanie Zhang]

Steps to reproduce:

Filing this as a tracking bug for implementing FormControlRange.

Implement FormControlRange -- a specialized, live AbstractRange subclass for <input>/<textarea> value space. It enables range-based operations in native controls while restricting standard Range mutations to preserve encapsulation. It integrates cleanly with existing selection/editing behavior and closes a long-standing gap.

Explainer: https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/FormControlRange/explainer.md

Ongoing WHATWG discussion thread: https://github.com/whatwg/html/issues/11478

Mozilla Standards Link: https://github.com/mozilla/standards-positions/issues/1289

Comment 1

[Stephanie Zhang]

Updating this bug to reflect the current proposal.

The proposal has evolved from FormControlRange into OpaqueRange. OpaqueRange is a specialized, live AbstractRange subtype whose boundary points reference internal nodes within host-defined elements (for example, <input>/<textarea> today, with a path to custom elements in the future). It enables range-based operations over encapsulated content while avoiding exposure of internal DOM nodes.

The proposal also updates AbstractRange so startContainer/endContainer can be null, allowing OpaqueRange to return null for those getters while Range and StaticRange continue to return nodes.

Updated explainer:
https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/OpaqueRange/explainer.md

Current specification work:
https://github.com/whatwg/dom/pull/1404
https://github.com/whatwg/html/pull/11741

Relevant WHATWG discussion:
https://github.com/whatwg/html/issues/11478

Mozilla standards position issue:
https://github.com/WebKit/standards-positions/issues/541

Comment 2

[Stephanie Zhang]

Accidentally linked the Webkit standards position issue instead of Mozilla's -- should be https://github.com/mozilla/standards-positions/issues/1289

Comment 3

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1990256 - Part 1: Prepare AbstractRange for OpaqueRange. r=keithamus!,#dom-core

Refactor mIsDynamicRange to RangeType enum. Make startContainer/endContainer
nullable via BinaryName split. Add dom.opaque_range.enabled pref.

Comment 4

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1990256 - Part 2: Implement OpaqueRange with createValueRange and live offset tracking. r=keithamus!,smaug!,#dom-core

Implements OpaqueRange (dom.spec.whatwg.org/#interface-opaquerange) and its
HTML integration. OpaqueRange has two states: "live" (mStart/mEnd on the
anonymous text node) and "offset-only" (display:none / editor not init'd).

Offset tracking reconstructs user edits from beforeinput selection snapshots,
handles programmatic .value= as full replacement, and setRangeText with precise
offsets. Multi-range selections (Ctrl+click) are supported.

Comment 5

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1990256 - Part 3: Wire OpaqueRange highlight painting and highlightsFromPoint. r=keithamus!,#dom-core

OpaqueRange lives in the text control's UA shadow DOM with its own
nsFrameSelection. Mirror OpaqueRanges into that internal frame selection
for highlight painting, and redirect Add/RemoveHighlightSelectionRange
to the correct frame selection.

Comment 6

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1990256 - Part 4: Add OpaqueRange geometry and highlight painting tests. r=keithamus!,#dom-core

Comment 7

[Jan Jaeschke [:jjaschke]]

Attachment: Bug 1990256 - Part 5: Update WPT test expectations. r=keithamus!,#dom-core