LGTM2 On Tue, Jun 30, 2026, 5:36 AM Yoav Weiss (@Shopify) <[email protected]> wrote:
> LGTM1 > > Please make sure the PRs land. (and delay shipping if the final round ends > up changing the API shape) > > On Friday, June 26, 2026 at 1:31:35 AM UTC+2 [email protected] wrote: > >> I’ve resolved all spec issues raised in prior rounds of review. The PRs >> received no more feedback for a couple weeks after the last review round, >> so I raised a request in the WHATNOT call today asking for any final >> feedback. Anne said he’d take another look so just waiting on that. >> >> >> >> In that discussion Olli from Mozilla asked I make sure the test coverage >> was complete. I think the existing test coverage is solid but am working on >> adding one specific case he asked for in >> https://chromium-review.googlesource.com/c/chromium/src/+/8007785. >> >> >> >> No other blockers that I know of except what a final review pass might >> turn up. >> >> >> >> *From:* Chris Harrelson <[email protected]> >> *Sent:* Thursday, June 25, 2026 1:16 PM >> *To:* Daniel Clark <[email protected]> >> *Cc:* [email protected] >> *Subject:* Re: [blink-dev] Intent to Ship: Reference Target >> >> >> >> Thanks for working on this API, it solves an important a11y and >> functional need. >> >> >> >> Given Mozilla is positive on this API, is there anything blocking landing >> the spec PRs? >> >> >> >> On Tue, Jun 23, 2026 at 4:22 PM 'Daniel Clark' via blink-dev < >> [email protected]> wrote: >> >> *Contact emails* >> >> [email protected], [email protected] >> >> *Explainer* >> >> >> https://github.com/WICG/webcomponents/blob/gh-pages/proposals/reference-target-explainer.md >> >> >> >> *Specification* >> >> https://github.com/whatwg/html/pull/10995, >> https://github.com/whatwg/dom/pull/1353 >> >> *Summary* >> >> Reference Target enables ID attributes like <label for>, >> 'aria-labelledby', 'popovertarget', and 'commandfor' to be forwarded to >> elements inside a component's shadow DOM, while maintaining the shadow's >> encapsulation of its internal state. When a shadow host specifies an >> element in its shadow tree to act as its reference target, all ID >> references pointing to the shadow host are forwarded to the reference >> target element instead. >> >> >> >> For example, here the <label>’s “my-checkbox” ID reference is forwarded >> to the element in the shadow with the ID “real-checkbox": >> >> >> >> <label for="my-checkbox">Click me to toggle checkbox</label> >> >> <custom-checkbox id="my-checkbox"> >> >> <template shadowrootmode="open" shadowrootreferencetarget="real-checkbox"> >> >> <input id="real-checkbox" type="checkbox"> >> >> </template> >> >> </custom-checkbox> >> >> >> >> Reference target can be set declaratively like in the above example, or >> in JavaScript with ShadowRoot's 'referenceTarget' property. >> >> *Blink component* >> >> Blink>DOM>ShadowDOM >> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EDOM%3EShadowDOM%22> >> >> *Web Feature ID* >> >> referencetarget <https://webstatus.dev/features/referencetarget> >> >> *Motivation* >> >> Shadow DOM presents a problem for accessibility: there is not a way to >> establish semantic relationships between elements in different shadow trees >> (such as via 'aria-labelledby'). This limits the ability to design web >> components in a way that works with accessibility tools such as screen >> readers. The ARIAMixin IDL attributes ( >> https://w3c.github.io/aria/#ARIAMixin) are a partial solution to the >> problem; however, they lack the ability to create a reference "into" a >> shadow tree from the outside. Reference Target is a solution to that >> missing piece of the problem. >> >> >> >> In addition to the issues with accessibility, ID attributes like >> 'popovertarget' and 'commandfor' can’t be used to refer to elements inside >> a shadow root without reference target. >> >> *Initial public proposal* >> >> https://github.com/WICG/aom/pull/207 >> >> *TAG review* >> >> https://github.com/w3ctag/design-reviews/issues/961 >> >> *TAG review status* >> >> Issues addressed >> >> *Origin Trial Name* >> >> Reference Target for Cross-Root ARIA >> >> *Chromium Trial Name* >> >> ShadowRootReferenceTarget >> >> *WebFeature UseCounter name* >> >> WebDXFeature::kDRAFT_ReferenceTarget >> >> *Risks* >> >> >> >> *Interoperability and Compatibility* >> >> The interoperability risk is low since engineers from the other browser >> engines have been active in spec discussions about the feature. >> >> >> >> This feature makes a change to the Toggle, Command, Interest, and Submit >> events that presents a small compatibility risk. These events each have a >> 'source'/'submitter' property that's set to the element triggering the >> event, e.g. the button element clicked to open a popup. With reference >> target this element can now be in a parent shadow tree relative to the >> event is fired. Per discussion in >> https://github.com/WICG/webcomponents/issues/1098 there was a desire to >> have the event's dispatch path include the source/submitter's tree. This is >> done by setting these events' internal relatedTarget ( >> https://dom.spec.whatwg.org/#event-relatedtarget) to >> their 'source'/'submitter' >> >> and making the event composed when that relatedTarget is non-null. When >> used with reference target this causes the event path to include a >> 'source'/'submitter' in a parent shadow. >> >> >> >> When used without reference target, there is no change to these events' >> event paths (since the source/submitter can never be in a parent shadow, >> therefore the relatedTarget will be in the same tree as the target, >> therefore the event won’t dispatch in the parent shadow per the current >> event dispatch algorithm). But, the 'composed' property on the event will >> be set to true. This has already been changed in the past for Command and >> Interest events ( >> https://chromium-review.googlesource.com/c/chromium/src/+/6505682, >> https://chromium-review.googlesource.com/c/chromium/src/+/7797864), and >> there's also history of changing these for Mouse events ( >> https://chromium-review.googlesource.com/c/chromium/src/+/4563502), so >> I'm optimistic that this won't cause breakage. Most usage on Github ( >> https://github.com/search?q=%2Fevent%5C.composed%5B%5EP%5D%2F&type=code) >> is either conditional on 'bubbles' also being true, which is false for the >> events in question, or is or is specific to mouse events which aren't >> affected here. >> >> *Gecko*: Positive ( >> https://github.com/mozilla/standards-positions/issues/1035) >> >> *WebKit*: No signal ( >> https://github.com/WebKit/standards-positions/issues/356) >> >> *Web developers*: Positive >> >> - Why we still need reference target >> <https://gist.github.com/davatron5000/b6a62cb782f01c69e818cd4585391138> >> - >> https://github.com/WICG/webcomponents/issues/1120#issuecomment-4156132737 >> - Lots of positive reactions on last year's Interop Project proposal >> for Reference Target, despite the feature not yet being eligible for the >> Interop Project at that time: >> https://github.com/web-platform-tests/interop/issues/1011 >> >> >> >> We ran an Origin Trial for the feature back in 133-135 but didn’t get >> much developer uptake at the time. I attribute this to the difficulty of >> poylfilling — see Activation section. We’ve since worked closely with >> developers to ensure that the API meets their needs and they’ll be able to >> adopt it. >> >> >> >> >> >> *Activation* >> >> This is a difficult feature to polyfill since ID reference attributes >> cannot pierce into shadow roots without it. So there's no way for a >> polyfill to enable the capability that reference target enables. My hope is >> that this will be mitigated by other browsers shipping the feature. Gecko >> is positive, I've been discussing the spec changes with engineers from both >> Gecko and WebKit, and Gecko and WebKit both have prototype implementations. >> >> >> >> There is already brief MDN documentation: >> >> >> https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/template#shadowrootreferencetarget >> >> >> https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot#shadowroot.referencetarget >> >> >> >> There has sometimes been confusion about what scenarios the feature >> unlocks, e.g. some developers assumed it directed ID references *out* of a >> shadow root rather than *into* a shadow root. I'll ensure that we have good >> documentation available including examples like those in >> https://microsoftedge.github.io/Demos/reference-target/. The MDN docs >> issue for the feature is still open at >> https://github.com/mdn/content/issues/43453. >> >> *WebView application risks* >> >> None >> >> >> >> *Debuggability* >> >> No specific DevTools support is expected to be necessary. Existing >> DevTools support for features used with reference target will continue to >> work. For example, the accessibility tree viewer can be used to check that >> an 'aria-labelledby' attribute is applied correctly even when it's used >> cross-shadow-DOM with reference target. >> >> *Will this feature be supported on all six Blink platforms (Windows, Mac, >> Linux, ChromeOS, Android, and Android WebView)?* >> >> Yes >> >> *Is this feature fully tested by **web-platform-tests* >> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >> *?* >> >> Yes: https://wpt.fyi/results/shadow-dom/reference-target >> >> *Flag name on about://flags* >> >> *No information provided* >> >> *Finch feature name* >> >> ShadowRootReferenceTarget >> >> *Rollout plan* >> >> Will ship enabled for all users >> >> *Requires code in //chrome?* >> >> False >> >> *Tracking bug* >> >> https://issues.chromium.org/issues/346835896 >> >> *Availability expectation* >> >> I've received positive engagement on the spec PR from WebKit and Gecko >> engineers, and the feature is prototyped in both of those engines. So I'm >> optimistic that they will follow in supporting this feature, though there >> is no official commitment of support. >> >> *Adoption expectation* >> >> We are working with a developer partner who plans to adopt the feature >> once it's shipped. >> >> *Non-OSS dependencies* >> >> None >> >> *Estimated milestones* >> >> Shipping on desktop >> >> 151 >> >> Origin trial desktop first >> >> 133 >> >> Origin trial desktop last >> >> 135 >> >> Shipping on Android >> >> 151 >> >> Shipping on WebView >> >> 151 >> >> >> >> *Anticipated spec changes* >> >> No breaking changes are expected. >> >> *Link to entry on the Chrome Platform Status* >> >> https://chromestatus.com/feature/5188237101891584?gate=5152828586196992 >> >> *Links to previous Intent discussions* >> >> Intent to Prototype: >> https://groups.google.com/a/chromium.org/g/blink-dev/c/CEdbbQXPIRk/m/U43spqbKAgAJ >> Intent to Experiment: >> https://groups.google.com/a/chromium.org/g/blink-dev/c/C3pELgMqzCY/m/Lpb6DkueAQAJ >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/DS0PR00MB2527DA9DA93A1972F5594156C5EE2%40DS0PR00MB2527.namprd00.prod.outlook.com >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/DS0PR00MB2527DA9DA93A1972F5594156C5EE2%40DS0PR00MB2527.namprd00.prod.outlook.com?utm_medium=email&utm_source=footer> >> . >> >> -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/4083781f-5237-46a3-993e-349ab4071a55n%40chromium.org > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/4083781f-5237-46a3-993e-349ab4071a55n%40chromium.org?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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