Proposed ARIA state or property is permitted

Description

This rule checks that WAI-ARIA states or properties are allowed for the element they are specified on.

Applicability

This rule applies to any WAI-ARIA state or property that is specified on an HTML or SVG element that is included in the accessibility tree.

Expectation 1

For each test target, one of the following is true:

• global: the test target is a global state or property; or
• semantic role: the test target is an inherited, supported, or required state or property of the semantic role of the element on which the test target is specified; or
• language feature: the test target is specified on an HTML element and is allowed on that element. Which ARIA states or properties may be used on which element is described in ARIA in HTML.

Expectation 2

No test target is prohibited on the semantic role of the element on which it is specified.

Assumptions

There are no assumptions.

Accessibility Support

Implementation of Presentational Roles Conflict Resolution varies from one browser or assistive technology to another. Depending on this, some elements can have a semantic role of none and their attributes fail this rule with some technologies but users of other technology would not experience any accessibility issue.

Background

The presence of prohibited ARIA attributes is often the result of a developer using an incorrect role, or a misunderstanding of the attribute. These attributes are ignored by browsers and other assistive technologies. This often means that a state or property which should exist is missing.

In HTML, there are language features that do not have corresponding implicit WAI-ARIA semantics. As per ARIA in HTML, those elements can have global states or properties. Some of those elements can also have inherited, supported, or required states or properties that correspond to a WAI-ARIA role. For example, the audio element has no corresponding ARIA semantics but it can have inherited, supported, or required states or properties of the application role.

Assessing the value of the attribute is out of scope for this rule.

Related rules

• ARIA state or property has valid value

Bibliography

• Understanding Success Criterion 4.1.1: Parsing
• Understanding Success Criterion 4.1.2: Name, Role, Value
• WAI-ARIA 1.2, Supported States and Properties
• WAI-ARIA 1.2, Global States and Properties
• ARIA5: Using WAI-ARIA state and property attributes to expose the state of a user interface component
• Document conformance requirements for use of ARIA attributes in HTML

Accessibility Requirements Mapping

• ARIA5: Using WAI-ARIA state and property attributes to expose the state of a user interface component

  • Learn more about technique ARIA5
  • Not required for conformance to any W3C accessibility recommendation.
  • Outcome mapping:
    • Any failed outcomes: technique is not satisfied
    • All passed outcomes: technique needs further testing
    • An inapplicable outcome: technique needs further testing
• This rule is not required for conformance to WCAG 2.1 at any level.

Secondary Requirements

This rule is related to the following accessibility requirements, but was not designed to test this requirements directly. These secondary requirements can either be stricter than the rule requires, or may be satisfied in ways not tested by the rule:

• 1.3.1 Info and Relationships (Level A): This success criterion is less strict than this rule. This is because the rule does not ignore irrelevant ARIA properties. Some of the failed examples satisfy this success criterion.
• 4.1.2 Name, Role, Value (Level A): This success criterion is less strict than this rule. This is because the rule does not ignore irrelevant ARIA properties. Some of the failed examples satisfy this success criterion.

Input Aspects

The following aspects are required in using this rule.

• Accessibility Tree
• CSS styling
• DOM Tree

Test Cases

Passed

Passed Example 1

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The aria-pressed state is supported with button, which is the implicit role for button elements.

<button aria-pressed="false">My button</button>

Passed Example 2

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The aria-pressed state is supported with button, which is the explicit role of this div element.

<div role="button" aria-pressed="false">My button</div>

Passed Example 3

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The aria-busy state is a global state that is supported by all elements, even without any semantic role.

<div aria-busy="true">My busy div</div>

Passed Example 4

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The aria-label property is a global property. It is allowed on any semantic role.

<div role="button" aria-label="OK">✓</div>

Passed Example 5

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The aria-checked state is required for the semantic checkbox.

<div role="checkbox" aria-checked="false">My checkbox</div>

Passed Example 6

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The aria-controls property is required for the semantic combobox.

<div role="combobox" aria-controls="id1" aria-expanded="false">My combobox</div>

Passed Example 7

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The aria-controls property is required for the semantic combobox. WAI-ARIA states and properties with empty value are still applicable to this rule.

<div role="combobox" aria-expanded="false" aria-controls>My combobox</div>

Passed Example 8

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The aria-controls property is required for the semantic combobox. WAI-ARIA states and properties with empty value (specified as an empty string) are still applicable to this rule.

<div role="combobox" aria-expanded="false" aria-controls="">My combobox</div>

Passed Example 9

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The aria-label property is global. It is allowed on any semantic role, including roles from the WAI-ARIA Graphics Module. This rule is applicable to SVG elements.

<svg xmlns="http://www.w3.org/2000/svg" role="graphics-object" width="100" height="100" aria-label="yellow circle">
	<circle cx="50" cy="50" r="40" fill="yellow"></circle>
</svg>

Passed Example 10

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This button element has an explicit role of none. However, because it is focusable (by default), it has a semantic role of button due to Presentational Roles Conflict Resolution. The aria-pressed state is supported for the button role.

<button role="none" aria-pressed="false">ACT rules are cool!</button>

Passed Example 11

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This input element does not have an explicit role of textbox, but the aria-required property may be used on an input element with a type attribute value of password.

<label>Password<input type="password" aria-required="true"/></label>

Failed

Failed Example 1

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The aria-sort property may not be used on a semantic button.

<button aria-sort="">Sort by year</button>

Failed Example 2

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The aria-orientation property may not be used on audio element, nor can it be used on application (the semantic role for which inherited, supported, or required states or properties are also applicable to audio element).

<audio src="/test-assets/moon-audio/moon-speech.mp3" controls aria-orientation="horizontal"></audio>

Failed Example 3

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The aria-label property is prohibited for an element with a generic role.

<div aria-label="Bananas"></div>

Inapplicable

Inapplicable Example 1

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This div element has no WAI-ARIA state or property.

<div role="region">A region of content</div>

Inapplicable Example 2

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This div element is not included in the accessibility tree, hence its WAI-ARIA state or property is not checked.

<div role="button" aria-sort="" style="display:none;"></div>

Glossary

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

• For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, “an input element with a type attribute value of Text” can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
• For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
• For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
• For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
• For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
• For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification and the HTML Accessibility API Mappings.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Explicit Semantic Role

The explicit semantic role of an element is determined by its role attribute (if any).

The role attribute takes a list of tokens. The explicit semantic role is the first valid role in this list. The valid roles are all non-abstract roles from WAI-ARIA Specifications. If the element has no role attribute, or if it has one with no valid role, then this element has no explicit semantic role.

Other roles may be added as they become available. Not all roles will be supported in all assistive technologies. Testers are encouraged to adjust which roles are allowed according to the accessibility support base line. For the purposes of executing test cases in all rules, it should be assumed that all roles are supported by assistive technologies so that none of the roles fail due to lack of accessibility support.

Focusable

An element is focusable if one or both of the following are true:

• the element is part of sequential focus navigation; or
• the element has a tabindex value that is not null.

Exception: Elements that lose focus during a period of up to 1 second after gaining focus, without the user interacting with the page the element is on, are not considered focusable.

Notes:

• The 1 second time span is an arbitrary limit which is not included in WCAG. Given that scripts can manage the focus state of elements, testing the focusability of an element consistently would be impractical without a time limit.
• The tabindex value of an element is the value of the tabindex attribute parsed using the rules for parsing integers. For the tabindex value to be different from null, it needs to be parsed without errors.

Implicit Semantic Role

The implicit semantic role of an element is a pre-defined value given by the host language which depends on the element and its ancestors.

Implicit roles for HTML and SVG, are documented in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

Marked as decorative

An element is marked as decorative if one or more of the following conditions is true:

• it has an explicit role of none or presentation; or
• it is an img element with an alt attribute whose value is the empty string (alt=""), and with no explicit role.

Elements are marked as decorative as a way to convey the intention of the author that they are pure decoration. It is different from the element actually being pure decoration as authors may make mistakes. It is different from the element being effectively ignored by assistive technologies as rules such as presentational roles conflict resolution may overwrite this intention.

Elements can also be ignored by assistive technologies if they are programmatically hidden. This is different from marking the element as decorative and does not convey the same intention. Notably, being programmatically hidden may change as users interact with the page (showing and hiding elements) while being marked as decorative should stay the same through all states of the page.

Namespaced Element

An element with a specific namespaceURI value from HTML namespaces. For example an “SVG element” is any element with the “SVG namespace”, which is http://www.w3.org/2000/svg.

Namespaced elements are not limited to elements described in a specification. They also include custom elements. Elements such as a and title have a different namespace depending on where they are used. For example a title in an HTML page usually has the HTML namespace. When used in an svg element, a title element has the SVG namespace instead.

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

• Inapplicable: No part of the test subject matches the applicability
• Passed: A test target meets all expectations
• Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such “interim” results can be expressed with the incomplete outcome.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

• has a computed CSS property display of none; or
• has an aria-hidden attribute set to true

Note: Contrary to the other conditions, the visibility CSS property may be reverted by descendants.

Note: The HTML standard suggests setting the CSS display property to none for elements with the hidden attribute. While not required by HTML, all modern browsers follow this suggestion. Because of this the hidden attribute is not used in this definition. In browsers that use this suggestion, overriding the CSS display property can reveal elements with the hidden attribute.

Semantic Role

The semantic role of an element is determined by the first of these cases that applies:

1. Conflict If the element is marked as decorative, but the element is included in the accessibility tree; or would be included in the accessibility tree when it is not programmatically hidden, then its semantic role is its implicit role.
2. Explicit If the element has an explicit role, then its semantic role is its explicit role.
3. Implicit The semantic role of the element is its implicit role.

This definition can be used in expressions such as “semantic button” meaning any element with a semantic role of button.

WAI-ARIA specifications

The WAI ARIA Specifications group both the WAI ARIA W3C Recommendation and ARIA modules, namely:

• Accessible Rich Internet Applications (WAI-ARIA) 1.2
• WAI-ARIA Graphics Module 1.0
• Digital Publishing WAI-ARIA Module 1.0

Note: depending on the type of content being evaluated, part of the specifications might be irrelevant and should be ignored.

Rule Versions

This is the first version of this ACT rule.

Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date.

Implementation	Type	Consistency	Report
Alfa (fully automated) 0.80.0	Automated tool	Consistent
Alfa (semi-automated) 0.80.0	Semi-automated tool	Consistent
Axe DevTools Pro 4.37.1	Semi-automated tool	Consistent
Axe-core 4.8.3	Automated tool	Consistent
Equal Access Accessibility Checker 3.1.42-rc.0	Automated tool	Consistent
QualWeb 3.0.0	Automated tool	Consistent
SortSite 6.45	Automated tool	Consistent
Total Validator 17.4.0	Linter	Consistent
Total Validator (+Browser) 17.4.0	Automated tool	Consistent
ember-template-lint 5.5.1	Linter	Partial

Useful Links

• Github issues related to this rule
• Open a new issue
• Propose a change to the rule