[combobox] Document and improve input click + list options filtering

[silviuaavram]

Closes #3442.

Implements what we discussed in this comment.

Improve combobox click, focus, and filter guidance

Changes

Behavior (combobox-autocomplete.js)

• Show all options when the trimmed input value is empty or exactly matches an option (case-insensitive); filter otherwise.

Pattern documentation (combobox-pattern.html)

• Replace "focus opens popup" with "click opens popup but does not toggle it closed".
• Add bullet for the chevron/toggle button, which toggles the popup open or closed.
• Extend filtering description to clarify trimmed-value and exact-match behavior.

Example pages (combobox-autocomplete-{both,list,none}.html)

• Add textbox-filter row to the keyboard table (list/both examples) documenting filter and show-all conditions.
• Add new Pointer Interaction section with separate Textbox and Button subsections covering click, focus, and toggle behaviors.

Regression tests (combobox_autocomplete-{both,list,none}.js)

• textbox-click: clicking the input opens the popup and a second click does not close it.
• textbox-focus: focusing the input without clicking does not open the popup.
• textbox-filter (list/both): verifies all options shown for empty input, exact match, case-insensitive exact match, and whitespace-only input; verifies filtered count (2) for partial string "al".

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WAI Preview Link (Last built on Mon, 15 Jun 2026 08:51:49 GMT).

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Updates the combobox autocomplete examples to refine open/close behavior on pointer interaction and adjust filtering behavior to avoid filtering when the input is empty or already matches an available option.

Changes:

• Updated ComboboxAutocomplete click handling so repeated textbox clicks don’t toggle the popup closed.
• Updated filtering logic so empty input (and exact-match input) shows the full option list.
• Added/updated automated tests and documentation tables describing new pointer/keyboard behaviors; refreshed coverage-report artifacts.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
test/tests/combobox_autocomplete-none.js	Adds tests for textbox click/focus pointer interaction behavior.
test/tests/combobox_autocomplete-list.js	Adds pointer interaction tests and new filtering-behavior test cases.
test/tests/combobox_autocomplete-both.js	Adds pointer interaction tests and new filtering-behavior test cases.
content/patterns/combobox/examples/js/combobox-autocomplete.js	Adjusts click-to-open behavior and expands “no filtering” conditions.
content/patterns/combobox/examples/combobox-autocomplete-none.html	Documents pointer interaction semantics for textbox/button.
content/patterns/combobox/examples/combobox-autocomplete-list.html	Documents pointer interaction + adds keyboard doc row for filtering behavior.
content/patterns/combobox/examples/combobox-autocomplete-both.html	Documents pointer interaction + adds keyboard doc row for filtering behavior.
content/patterns/combobox/combobox-pattern.html	Updates pattern-level narrative re: filtering and popup opening interactions.
content/about/coverage-and-quality/role-coverage.csv	Updates generated counts/entries for role coverage.
content/about/coverage-and-quality/coverage-and-quality-report.html	Updates generated role report list (adds a new “note” link).

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