angular / angular/components

bug(CDK a11y, Tooltip, SortHeader): AriaDescriber not working inside Shadow DOM

Aperta
#24,919 2 commenti 2 reazioni 0 assegnatari Vedi su GitHub
area: cdk/a11y P4
Lingua principale
TypeScript
Stelle
25k
Fork
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Merge medio
1g 8h
PR unite (30g)
91

Descrizione

### Is this a regression?

- [ ] Yes, this behavior used to work in the previous version

### The previous version in which this bug was not present was

_No response_

### Description

The AriaDescriber service creates a container element and appends it to the body. The messages inside the container are linked with the host element using `aria-describedby` when calling `ariaDescriber.describe()`.

When the host element is inside Shadow DOM this will not work properly because the hidden message element (that is referenced via `aria-describedby`) is outside of the Shadow DOM and will be ignored by the browser.

### Reproduction

I actually had the problem with Angular Material Tooltips and Table Sort Header (which use AriaDescriber) but for the repro I use the AriaDescriber service directly. I set a description on a button in the Example component which uses `ViewEncapsulation.ShadowDom`.

Steps to reproduce:
1. Open the repro https://stackblitz.com/edit/components-issue-rxwpmf?file=src/app/example-component.ts
2. Inspect the "Action" button
3. Open the "Accessibility" tab in the inspector

### Expected Behavior

The button should have the description "Some description" which was created via AriaDescriber service.

### Actual Behavior

The button has no description.

![aria-describer-shadowdom](https://user-images.githubusercontent.com/16229645/168264055-4cc41d97-977d-4f3b-a7fd-175242f9ad4a.png)

The `aria-describedby` attribute is there but the referenced element is ignored because it's outside of the Shadow DOM. It works if I set `encapsulation` on the component to `Emulated`.

### Environment

- Angular: 13.3.0
- CDK/Material: 13.3.0
- Browser(s): Brave
- Operating System (e.g. Windows, macOS, Ubuntu): macOS

Guida per i contributori

Apri la guida per i contributori

Direzione di ricerca

Inizia con il servizio AriaDescriber e riproduci il problema usando l’esempio StackBlitz collegato con ViewEncapsulation.ShadowDom. Verifica il comportamento tramite l’Inspector di accessibilità del browser; il lavoro è completato quando il pulsante espone “Some description” mantenendo l’incapsulamento Shadow DOM.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Valutazione

Stack tecnologico
angular, typescript
Ambito
accessibility, frontend
Tipo di issue
Bug
Difficoltà
3/5
Tempo stimato
1-2 giorni
Stato di attività
Attiva
Chiarezza
Abbastanza chiara
Idoneità per principianti
55/100

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