accessibility-scanner

A TypeScript accessibility scanner aimed at being W3C ACT (Accessibility Conformance Testing) rules compatible. Rules from axe-core that aren't yet codified in ACT are implemented in a separate section.

ACT Rules

Implementation status against the ACT Rules Community Group catalogue. Each rule links to its ACT specification. The Test cases column shows how many of the ACT-supplied test cases this scanner runs and passes — out of the total applicable cases for that rule. Test cases that depend on visual rendering, media playback, keyboard interaction, or other capabilities outside the scanner's scope are intentionally not generated.

The W3C ACT implementations report only counts a rule as "consistently implemented" when the implementation passes every published ACT test case for it. By that measure:

• 20 ACT rules pass every generated test case (W3C "consistent implementation" criterion).
• 14 more rules pass at least one test case but not all.
• 53 / 88 ACT rules have some scanner implementation, even if untested.
• 296 / 843 ACT test cases (35%) are exercised against the scanner.

Implemented	ACT Rule	WCAG	axe-core rule(s)	Test cases
✅	73f2c2 — autocomplete attribute has valid value	1.3.5	autocomplete-valid	0 / 19
✅	5f99a7 — ARIA attribute is defined in WAI-ARIA	1.3.1, 4.1.2	aria-valid-attr	7 / 7
❌	kb1m8s — ARIA global properties not used where prohibited	1.3.1	—	0 / 8
✅	ff89c9 — ARIA required context role	1.3.1	aria-required-parent	0 / 10
✅	bc4a75 — ARIA required owned elements	1.3.1	aria-required-children	0 / 20
✅	6a7281 — ARIA state or property has valid value	1.3.1, 4.1.2	aria-valid-attr-value	0 / 17
✅	5c01ea — ARIA state or property is permitted	1.3.1, 4.1.2	aria-allowed-attr	0 / 15
❌	1a02b0 — Audio and visuals of video element have transcript	1.2.1, 1.2.8, 1.3.1	—	0 / 8
❌	e7aa44 — Audio element content has text alternative	1.2.1	—	0 / 5
✅	2eb176 — Audio element content has transcript	—	audio-caption	0 / 9
✅	afb423 — Audio element content is media alternative for text	—	audio-caption	0 / 5
✅	80f0bf — Audio or video element avoids automatically playing audio	1.4.2	no-autoplay-audio	4 / 5
❌	4c31df — Audio or video element that plays automatically has a control mechanism	—	—	0 / 8
❌	aaa1bf — Audio or video element that plays automatically has no audio that lasts more than 3 seconds	—	—	0 / 4
✅	3e12e1 — Block of repeated content is collapsible	—	bypass	3 / 7
✅	97a4e1 — Button has non-empty accessible name	4.1.2	aria-command-name, button-name, input-button-name	12 / 12
✅	cf77f2 — Bypass Blocks of Repeated Content	2.4.1	bypass	9 / 13
❌	9bd38c — Content has alternative for visual reference	1.3.3	—	0 / 19
❌	7677a9 — Device motion based changes to the content can also be created from the user interface	2.5.4	—	0 / 5
❌	c249d5 — Device motion based changes to the content can be disabled	2.5.4	—	0 / 4
✅	b40fd1 — Document has a landmark with non-repeated content	—	bypass	0 / 7
✅	ye5d6e — Document has an instrument to move focus to non-repeated content	—	bypass	9 / 11
✅	047fe0 — Document has heading for non-repeated content	—	bypass	10 / 13
❌	oj04fd — Element in sequential focus order has visible focus	2.4.7	—	0 / 6
✅	46ca7f — Element marked as decorative is not exposed	—	presentation-role-conflict	9 / 9
✅	6cfa84 — Element with aria-hidden has no content in sequential focus navigation	4.1.2	aria-hidden-focus	11 / 12
✅	de46e4 — Element with lang attribute has valid language tag	3.1.2	valid-lang	14 / 14
✅	307n5z — Element with presentational children has no focusable content	4.1.2	nested-interactive	0 / 9
✅	4e8ab6 — Element with role attribute has required states and properties	1.3.1, 4.1.2	aria-required-attr	0 / 11
✅	36b590 — Error message describes invalid form field value	3.3.1	error-message	8 / 8
❌	80af7b — Focusable element has no keyboard trap	2.1.2	—	0 / 12
❌	ebe86a — Focusable element has no keyboard trap via non-standard navigation	—	—	0 / 6
❌	a1b64e — Focusable element has no keyboard trap via standard navigation	—	—	0 / 7
✅	e086e5 — Form field has non-empty accessible name	1.3.1, 2.5.3, 4.1.2	aria-input-field-name, aria-toggle-field-name, label, select-name	19 / 19
❌	cc0f0a — Form field label is descriptive	2.4.6	—	0 / 13
✅	a25f45 — Headers attribute specified on a cell refers to cells in the same table element	1.3.1	td-headers-attr	12 / 12
✅	ffd0e9 — Heading has non-empty accessible name	—	empty-heading	13 / 13
❌	b49b2e — Heading is descriptive	2.4.6	—	0 / 10
❌	off6ek — HTML element language subtag matches language	3.1.2	—	0 / 9
❌	0va7u6 — HTML images contain no text	1.4.5, 1.4.9	—	0 / 13
✅	bf051a — HTML page lang attribute has valid language tag	3.1.1	html-lang-valid	6 / 6
✅	b5c3f8 — HTML page has lang attribute	3.1.1	html-has-lang	5 / 5
✅	2779a5 — HTML page has non-empty title	2.4.2	document-title	12 / 12
❌	ucwvc8 — HTML page language subtag matches default language	3.1.1	—	0 / 9
❌	c4a8a4 — HTML page title is descriptive	2.4.2	—	0 / 6
✅	cae760 — Iframe element has non-empty accessible name	4.1.2	frame-title	0 / 7
✅	4b1c6c — Iframe elements with identical accessible names have equivalent purpose	4.1.2	frame-title-unique	0 / 14
✅	akn7bn — Iframe with interactive elements is not excluded from tab-order	2.1.1, 2.1.3	frame-focusable-content	3 / 3
❌	qt1vmo — Image accessible name is descriptive	1.1.1	—	0 / 6
✅	59796f — Image button has non-empty accessible name	1.1.1, 4.1.2	input-image-alt	0 / 7
❌	9eb3f6 — Image filename is accessible name for image	1.1.1	—	—
✅	23a2a8 — Image has non-empty accessible name	1.1.1	image-alt, role-img-alt	13 / 13
✅	e88epe — Image not in the accessibility tree is decorative	1.1.1	decorative-image	6 / 10
✅	24afc2 — Important letter spacing in style attributes is wide enough	1.4.12	avoid-inline-spacing	7 / 10
✅	78fd32 — Important line height in style attributes is wide enough	1.4.12	avoid-inline-spacing	11 / 14
✅	9e45ec — Important word spacing in style attributes is wide enough	1.4.12	avoid-inline-spacing	7 / 10
✅	c487ae — Link has non-empty accessible name	2.4.4, 2.4.9, 4.1.2	area-alt, link-name	12 / 22
❌	5effbb — Link in context is descriptive	2.4.4, 2.4.9	—	0 / 15
❌	aizyf1 — Link is descriptive	2.4.9	—	0 / 9
❌	fd3a94 — Links with identical accessible names and same context serve equivalent purpose	2.4.4, 2.4.9	—	0 / 17
✅	b20e66 — Links with identical accessible names have equivalent purpose	2.4.9	identical-links-same-purpose	0 / 18
✅	m6b1q3 — Menuitem has non-empty accessible name	4.1.2	button-name	6 / 6
✅	bc659a — Meta element has no refresh delay	2.2.1, 2.2.4, 3.2.5	meta-refresh	7 / 7
✅	bisz58 — Meta element has no refresh delay (no exception)	2.2.1, 2.2.4, 3.2.5	meta-refresh-no-exceptions	5 / 5
✅	b4f0c3 — Meta viewport allows for zoom	1.4.10, 1.4.4	meta-viewport	12 / 12
❌	ffbc54 — No keyboard shortcut uses only printable characters	2.1.4	—	0 / 8
✅	8fc3b6 — Object element rendering non-text content has non-empty accessible name	1.1.1	object-alt	10 / 10
✅	b33eff — Orientation of the page is not restricted using CSS transforms	1.3.4	css-orientation-lock	0 / 7
✅	674b10 — Role attribute has valid value	1.3.1, 4.1.2	aria-roles	0 / 5
✅	0ssw9k — Scrollable content can be reached with sequential focus navigation	2.1.1, 2.1.3	scrollable-region-focusable	4 / 6
✅	2t702h — Summary element has non-empty accessible name	4.1.2	summary-name	8 / 8
✅	7d6734 — SVG element with explicit role has non-empty accessible name	1.1.1	svg-img-alt	0 / 7
✅	d0f69e — Table header cell has assigned cells	1.3.1	th-has-data-cells	9 / 9
❌	efbfc7 — Text content that changes automatically can be paused, stopped or hidden	2.2.2	—	0 / 6
✅	09o5cg — Text has enhanced contrast	1.4.3, 1.4.6	color-contrast-enhanced	0 / 24
✅	afw4f7 — Text has minimum contrast	1.4.3, 1.4.6	color-contrast	0 / 23
✅	eac66b — Video element auditory content has accessible alternative	1.2.2	video-caption	3 / 4
❌	f51b46 — Video element auditory content has captions	1.2.1	—	0 / 6
❌	ab4d13 — Video element content is media alternative for text	—	—	0 / 5
❌	c5a4ea — Video element visual content has accessible alternative	1.2.3, 1.2.5, 1.2.8	—	0 / 7
❌	1ea59c — Video element visual content has audio description	—	—	0 / 5
❌	1ec09b — Video element visual content has strict accessible alternative	1.2.5	—	0 / 5
❌	c3232f — Video element visual-only content has accessible alternative	1.2.1	—	0 / 7
❌	d7ba54 — Video element visual-only content has audio track alternative	—	—	0 / 3
❌	ee13b5 — Video element visual-only content has transcript	1.2.1, 1.3.1	—	0 / 6
❌	fd26cf — Video element visual-only content is media alternative for text	—	—	0 / 5
✅	2ee8b8 — Visible label is part of accessible name	2.5.3	label-content-name-mismatch	10 / 11
❌	59br37 — Zoomed text node is not clipped with CSS overflow	1.4.4	—	0 / 9

Axe-core Specific Rules — WCAG 2.0 Level A & AA Rules

Rules implemented from the axe-core ruleset that don't have an equivalent in the ACT catalogue.

Implemented	axe-core Rule	Description	Tags	Impact	Issue Type
✅	aria-hidden-body	Ensures aria-hidden='true' is not present on the document body.	wcag2a, wcag412	Critical	failure
✅	aria-meter-name	Ensures every ARIA meter node has an accessible name	wcag2a, wcag111	Serious	failure, needs review
✅	aria-progressbar-name	Ensures every ARIA progressbar node has an accessible name	wcag2a, wcag111	Serious	failure, needs review
✅	aria-roledescription	Ensure aria-roledescription is only used on elements with an implicit or explicit role	wcag2a, wcag412	Serious	failure, needs review
✅	aria-tooltip-name	Ensures every ARIA tooltip node has an accessible name	wcag2a, wcag412	Serious	failure, needs review
✅	blink	Ensures <blink> elements are not used	wcag2a, wcag222, section508, section508.22.j	Serious	failure
✅	definition-list	Ensures <dl> elements are structured correctly	wcag2a, wcag131	Serious	failure
✅	dlitem	Ensures <dt> and <dd> elements are contained by a <dl>	wcag2a, wcag131	Serious	failure
✅	form-field-multiple-labels	Ensures form field does not have multiple label elements	wcag2a, wcag332	Moderate	needs review
✅	list	Ensures that lists are structured correctly	wcag2a, wcag131	Serious	failure
✅	listitem	Ensures <li> elements are used semantically	wcag2a, wcag131	Serious	failure
✅	marquee	Ensures <marquee> elements are not used	wcag2a, wcag222	Serious	failure
✅	server-side-image-map	Ensures that server-side image maps are not used	wcag2a, wcag211, section508, section508.22.f	Minor	needs review

Axe-core Specific Rules — WCAG 2.1 Level A & AA Rules

Rules implemented from the axe-core ruleset that don't have an equivalent in the ACT catalogue.

Implemented	axe-core Rule	Description	Tags	Impact	Issue Type
✅	target-size	Ensure touch target have sufficient size and space	wcag22aa, sc258	Serious	failure

Axe-core Specific Rules — Best Practices Rules

Rules that do not necessarily conform to WCAG success criterion but are industry accepted practices that improve the user experience.

Implemented	axe-core Rule	Description	Tags	Impact	Issue Type
✅	accesskeys	Ensures every accesskey attribute value is unique	best-practice	Serious	failure
✅	aria-allowed-role	Ensures role attribute has an appropriate value for the element	best-practice	Minor	failure, needs review
✅	aria-dialog-name	Ensures every ARIA dialog and alertdialog node has an accessible name	best-practice	Serious	failure, needs review
✅	aria-text	Ensures "role=text" is used on elements with no focusable descendants	best-practice	Serious	failure, needs review
✅	aria-treeitem-name	Ensures every ARIA treeitem node has an accessible name	best-practice	Serious	failure, needs review
✅	empty-table-header	Ensures table headers have discernible text	best-practice	Minor	failure, needs review
✅	frame-tested	Ensures <iframe> and <frame> elements have been tested for accessibility	best-practice	Critical	failure, needs review
✅	heading-order	Ensures the order of headings is semantically correct	best-practice	Moderate	failure, needs review
✅	image-redundant-alt	Ensure image alternative is not repeated as text	best-practice	Minor	failure
✅	label-title-only	Ensures that every form element has a visible label and is not solely labeled using hidden labels, or the title or aria-describedby attributes	best-practice	Serious	failure
✅	landmark-banner-is-top-level	Ensures the banner landmark is at top level	best-practice	Moderate	failure
✅	landmark-complementary-is-top-level	Ensures the complementary landmark or aside is at top level	best-practice	Moderate	failure
✅	landmark-contentinfo-is-top-level	Ensures the contentinfo landmark is at top level	best-practice	Moderate	failure
✅	landmark-main-is-top-level	Ensures the main landmark is at top level	best-practice	Moderate	failure
✅	landmark-no-duplicate-banner	Ensures the document has at most one banner landmark	best-practice	Moderate	failure
✅	landmark-no-duplicate-contentinfo	Ensures the document has at most one contentinfo landmark	best-practice	Moderate	failure
✅	landmark-no-duplicate-main	Ensures the document has at most one main landmark	best-practice	Moderate	failure
✅	landmark-one-main	Ensures the document has a main landmark	best-practice	Moderate	failure
✅	landmark-unique	Landmarks should have a unique role or role/label/title (i.e. accessible name) combination	best-practice	Moderate	failure
✅	meta-viewport-large	Ensures <meta name="viewport"> can scale a significant amount	best-practice	Minor	failure
✅	page-has-heading-one	Ensure that the page, or at least one of its frames contains a level-one heading	best-practice	Moderate	failure
✅	region	Ensures all page content is contained by landmarks	best-practice	Moderate	failure
✅	scope-attr-valid	Ensures the scope attribute is used correctly on tables	best-practice	Moderate, Critical	failure
✅	skip-link	Ensure all skip links have a focusable target	best-practice	Moderate	failure, needs review
✅	tabindex	Ensures tabindex attribute values are not greater than 0	best-practice	Serious	failure
✅	table-duplicate-name	Ensure the <caption> element does not contain the same text as the summary attribute	best-practice	Minor	failure, needs review

Axe-core Specific Rules — Experimental Rules

Rules we are still testing and developing. They are disabled by default.

Implemented	axe-core Rule	Description	Tags	Impact	Issue Type
✅	focus-order-semantics	Ensures elements in the focus order have a role appropriate for interactive content	best-practice, experimental	Minor	failure
✅	hidden-content	Informs users about hidden content.	experimental, best-practice	Minor	failure, needs review
✅	link-in-text-block	Ensure links are distinguished from surrounding text in a way that does not rely on color	experimental, wcag2a, wcag141	Serious	failure, needs review
✅	p-as-heading	Ensure bold, italic text and font-size is not used to style <p> elements as a heading	wcag2a, wcag131, experimental	Serious	failure, needs review
✅	table-fake-caption	Ensure that tables with a caption use the <caption> element.	experimental, wcag2a, wcag131, section508, section508.22.g	Serious	failure
✅	td-has-header	Ensure that each non-empty data cell in a <table> larger than 3 by 3 has one or more table headers	experimental, wcag2a, wcag131, section508, section508.22.g	Critical	failure

Custom Rules

Rules implemented in this scanner that are not part of any external rule set. These are not included in the default rule set due to higher false-positive rates. To use them, import and pass them explicitly:

import { Scanner } from "@koddsson/accessibility-scanner";
import errorMessage from "@koddsson/accessibility-scanner/rules/error-message";

const scanner = new Scanner([...allRules, errorMessage]);

Implemented	Rule	Description	Tags	Impact	Issue Type
✅	error-message	Ensures that error messages are programmatically associated with form fields	wcag2a, wcag331, ACT	Moderate	failure