web-a11y-web-components

Make accessible usage the easiest component API, provide a usable light DOM fallback, keep slot order aligned with semantic reading order, and delegate focus intentionally. Validate required labels and relationships at runtime and verify with keyboard and screen reader testing.

Focus delegation behavior must be intentional and documented as part of the component contract. Decide whether focus lands on the host or an internal element, then verify the behavior manually with keyboard navigation since automated tools may miss Shadow DOM focus issues.

ARIA relationships that reference elements across shadow roots are unreliable and should be avoided. Do not depend on cross-root ID references; instead keep relationships within one root or use ElementInternals where supported.

Automated scanners vary widely in Shadow DOM coverage, so they can miss focus, labeling, and reading-order problems inside components. Pair automation with manual keyboard checks and screen reader smoke tests for reliable results.

Include a usable fallback or failure mode, slot order matching semantic reading order, documented and enforced accessibility inputs, intentional focus delegation, no unsupported cross-root ARIA, and manual keyboard plus screen reader verification.