accessibility-aria-expert

作者： microsoft

偵測並修復 React/Fluent UI 網頁檢視中的無障礙問題。用於審查程式碼的螢幕閱讀器相容性、修正 ARIA 標籤、確保…

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Accessibility Expert for Webviews

Verify and fix accessibility in React/Fluent UI webview components.

When to Use

Review webview code for accessibility issues
Fix double announcements from screen readers
Add missing aria-label to icon-only buttons or form inputs
Make tooltips accessible to keyboard/screen reader users
Announce status changes (loading, search results, errors)
Manage focus when dialogs/modals open
Group related controls with proper labels

Core Pattern: Tooltip Accessibility

Tooltips require aria-label + aria-hidden to avoid double announcements:

<Tooltip content="Detailed explanation">
  <Badge tabIndex={0} className="focusableBadge" aria-label="Badge text. Detailed explanation">
    <span aria-hidden="true">Badge text</span>
  </Badge>
</Tooltip>

aria-label: Full context (visible text + tooltip)
aria-hidden="true": Wraps visible text to prevent duplication
Screen reader hears: "Badge text. Detailed explanation"

Required Accessible-Name Audit

For every interactive element with visible text, compare the rendered text with its computed accessible name. Check all sources that can override descendant text, including aria-label, aria-labelledby, title, and Fluent UI tooltips with relationship="label".

The computed accessible name must contain the exact localized visible text. Additional context may follow or precede it.
Prefer visible descendant text as the native accessible name. For a simple flat-text description, use aria-description so the visible label remains the name without adding hidden DOM content. Use aria-describedby when the description already exists in the DOM, is shared by multiple controls, contains meaningful structure, or compatibility requirements demand it. Add aria-label only when the accessible name itself needs clarification, and include the exact visible label when doing so.
When adding context, derive both strings from the same localized visible-label variable. Do not translate the visible and accessible labels independently because translations can drift.
Remember that aria-label overrides descendant text. Seeing the visible label inside the component does not mean it is included in the accessibility tree.
Review existing accessible-name attributes when modifying a control, even when the change does not add or alter ARIA.

For user-facing controls covered by Playwright, assert both the rendered label and computed accessible name:

const moreLabel = page.getByRole('button', { name: /^More/ });
await expect(moreLabel).toHaveText('More…');
await expect(moreLabel).toHaveAccessibleName(/^More…/);
await expect(moreLabel).toHaveAccessibleDescription('Show full description');

Avoid Hidden-Text Scroll Regressions

Do not add an absolutely positioned screen-reader-only element just to name a nearby semantic element, especially inside a scrollable table, grid, list, or panel. VoiceOver may move the virtual cursor to the hidden element's layout box and scroll the visible content out of view.

Prefer setting the accessible name or description on a rendered element with useful on-screen bounds. For text controls, this is usually the semantic element itself. For an icon or symbol inside a table cell, use a visible inline wrapper as the named accessibility node and keep the visual-only child hidden from assistive technology:

// ❌ VoiceOver may scroll to the hidden span when navigating the cell.
<td>
  <span className={styles.srOnly}>{l10n.t('Yes')}</span>
  <CheckmarkCircleFilled />
</td>

// ❌ The value is announced, but VoiceOver's visual focus indicator may disappear from the rendered symbol.
<td aria-label={l10n.t('Yes')}>
  <CheckmarkCircleFilled aria-hidden={true} />
</td>

// ✅ The accessibility node uses the visible symbol's bounds; there is no off-screen layout box to reveal.
<td>
  <span role="img" aria-label={l10n.t('Yes')} style={{ display: 'inline-flex' }}>
    <CheckmarkCircleFilled aria-hidden={true} />
  </span>
</td>

Use hidden DOM text only when the semantic relationship cannot be expressed directly. When it is necessary, use an established shared utility, anchor it to an appropriate containing block, and manually navigate the control with VoiceOver or NVDA to verify that focus and the virtual cursor do not scroll the visible content away or lose the visual focus indicator. Playwright accessible-name assertions do not detect these screen-reader-driven visual regressions.

Detection Rules

1. Tooltip Without aria-label Context

❌ Problem: Tooltip content inaccessible to screen readers

<Tooltip content="Save document to database">
  <Button aria-label="Save">Save</Button>
</Tooltip>

✅ Fix: Include tooltip in aria-label

<Tooltip content="Save document to database" relationship="description">
  <Button aria-label="Save document to database">Save</Button>
</Tooltip>

2. Missing aria-hidden (Double Announcement)

❌ Problem: Screen reader says "Collection scan Collection scan"

<Badge aria-label="Collection scan. Query is inefficient">Collection scan</Badge>

✅ Fix: Wrap visible text

<Badge aria-label="Collection scan. Query is inefficient">
  <span aria-hidden="true">Collection scan</span>
</Badge>

3. Redundant aria-label (NOT Needed)

❌ Problem: aria-label identical to visible text adds no value

<Button aria-label="Save">Save</Button>
<ToolbarButton aria-label="Validate" icon={<CheckIcon />}>Validate</ToolbarButton>

✅ Fix: Remove redundant aria-label OR make it more descriptive

<Button>Save</Button>
<ToolbarButton icon={<CheckIcon />}>Validate</ToolbarButton>

Keep aria-label only when it adds information:

<ToolbarButton aria-label="Save document to database" icon={<SaveIcon />}>
  Save
</ToolbarButton>

4. Icon-Only Button Missing aria-label

❌ Problem: No accessible name

<ToolbarButton icon={<DeleteRegular />} onClick={onDelete} />

✅ Fix: Add aria-label

<Tooltip content="Delete selected items" relationship="description">
  <ToolbarButton aria-label="Delete selected items" icon={<DeleteRegular />} onClick={onDelete} />
</Tooltip>

5. Decorative Elements Not Hidden

❌ Problem: Progress bar announced unnecessarily

<ProgressBar thickness="large" />

✅ Fix: Hide decorative elements

<ProgressBar thickness="large" aria-hidden={true} />

6. Input Missing Accessible Name

❌ Problem: SpinButton/Input without accessible name

<SpinButton value={skipValue} onChange={onSkipChange} />
<Input placeholder="Enter query..." />

✅ Fix: Add aria-label or associate with label element

<SpinButton aria-label="Skip documents" value={skipValue} onChange={onSkipChange} />
<Label htmlFor="query-input">Query</Label>
<Input id="query-input" placeholder="Enter query..." />

7. Visible Label Not in Accessible Name

❌ Problem: aria-label doesn't contain visible text (breaks voice control)

<ToolbarButton aria-label="Reload data" icon={<RefreshIcon />}>
  Refresh
</ToolbarButton>

✅ Fix: Accessible name must contain visible label exactly

<ToolbarButton aria-label="Refresh data" icon={<RefreshIcon />}>
  Refresh
</ToolbarButton>

Voice control users say "click Refresh" – only works if accessible name contains "Refresh".

8. Status Changes Not Announced

❌ Problem: Screen reader doesn't announce dynamic content

<span>{isLoading ? 'Loading...' : `${count} results`}</span>

✅ Fix: Use the Announcer component

import { Announcer } from '../../api/webview-client/accessibility';

// Announces when `when` transitions from false to true
<Announcer when={isLoading} message={l10n.t('Loading...')} />

// Dynamic message based on state
<Announcer
    when={!isLoading && documentCount !== undefined}
    message={documentCount > 0 ? l10n.t('Results found') : l10n.t('No results found')}
/>

Use for: loading states, search results, success/error messages.

9. Dialog Opens Without Focus Move

❌ Problem: Focus stays on trigger when modal opens

{
  isOpen && <Dialog>...</Dialog>;
}

✅ Fix: Move focus programmatically

const dialogRef = useRef<HTMLDivElement>(null);

useEffect(() => {
  if (isOpen) dialogRef.current?.focus();
}, [isOpen]);

{
  isOpen && (
    <Dialog ref={dialogRef} tabIndex={-1} aria-modal="true">
      ...
    </Dialog>
  );
}

10. Related Controls Without Group Label

❌ Problem: Buttons share visual label but screen reader misses context

<span>How would you rate this?</span>
<Button>👍</Button>
<Button>👎</Button>

✅ Fix: Use role="group" with aria-labelledby

<div role="group" aria-labelledby="rating-label">
  <span id="rating-label">How would you rate this?</span>
  <Button aria-label="I like it">👍</Button>
  <Button aria-label="I don't like it">👎</Button>
</div>

When to Use aria-hidden

DO use on:

Visible text when aria-label provides complete context
Decorative icons, spinners, progress bars
Visual separators (`|`, `—`)

DO NOT use on:

The only accessible content (hides it completely)
Interactive/focusable elements
Error messages or alerts

focusableBadge Pattern

For keyboard-accessible badges with tooltips:

Import: `import '../components/focusableBadge/focusableBadge.scss';`
Apply attributes:

<Badge tabIndex={0} className="focusableBadge" aria-label="Visible text. Tooltip details">
  <span aria-hidden="true">Visible text</span>
</Badge>

Screen Reader Announcements

Use the Announcer component for WCAG 4.1.3 (Status Messages) compliance.

import { Announcer } from '../../api/webview-client/accessibility';

Basic Usage

// Announces "AI is analyzing..." when isLoading becomes true
<Announcer when={isLoading} message={l10n.t('AI is analyzing...')} />

// Dynamic message based on state (e.g., query results)
<Announcer
    when={!isLoading && documentCount !== undefined}
    message={documentCount > 0 ? l10n.t('Results found') : l10n.t('No results found')}
/>

// With assertive politeness (default is polite)
<Announcer when={hasError} message={l10n.t('Error occurred')} politeness="assertive" />

Props

when: Announces when this transitions from false to true
message: The message to announce (use l10n.t() for localization)
politeness: 'assertive' (default, interrupts) or 'polite' (waits for idle)

Key Points

Placement doesn't matter - screen readers monitor all live regions regardless of DOM position; place near related UI for code readability
Store relevant state (e.g., documentCount) to derive dynamic messages
Use l10n.t() for messages - announcements must be localized
Condition resets automatically - when when goes back to false, it's ready for the next announcement
Prefer 'assertive' for user-initiated actions, 'polite' for background updates