ACT-Rules Community

Role attribute has valid value

  • Rule Type:atomic
  • Rule Id: 674b10
  • Last modified: Jan 11, 2022
  • Accessibility Requirements Mapping:
    • 1.3.1 Info and Relationships (Level A)
      • Learn More about 1.3.1 Info and Relationships
      • Required for conformance to WCAG 2.0 and later on level A and higher.
      • Outcome mapping:
        • Any failed outcomes: success criterion is not satisfied.
        • All passed outcomes: success criterion needs further testing.
        • An inapplicable outcome: success criterion needs further testing.
    • ARIA4: Using a WAI-ARIA role to expose the role of a user interface component
      • Learn More about technique ARIA4
      • Not required to 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.
    • G108: Using markup features to expose the name and role, allow user-settable properties to be directly set, and provide notification of changes
      • Learn More about technique G108
      • Not required to 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.
  • Input Aspects:

Description

This rule checks that each role attribute has a valid value.

Applicability

This rule applies to any role attribute for which all the following are true:

Expectation

Each test target has at least one token which is a valid value corresponding to a non-abstract role from WAI-ARIA Specifications.

Assumptions

  • This rule assumes that the role attribute is used to provide an ARIA semantic role to the elements. If it is used for other purposes, this rule shouldn't be used.
  • This rule assumes that elements with a role attribute have their intended structure and relationship conveyed through some sort of presentation. If it is not the case, it is possible to fail this rule while still satisfying Success Criterion 1.3.1 Info and Relationship.
  • This rule assumes that the intended role of the element is not its implicit role. If no token is valid, User Agents will default to the implicit role for the element; if that role is the intended one, it is possible to fail this rule but still satisfy Success Criterion 1.3.1 Info and Relationship.

Accessibility Support

Older browsers do not support more than one token in the value for a role attribute. If multiple values are used in the role attribute, the attribute is ignored in these browsers.

Background

The role attribute is a set of space separated tokens. Having a whitespace separated list of more than one token in the value of the role attribute is used for what is known as fallback roles. If the first token is not accessibility supported (or valid), the next one will be used for determining the semantic role of the element, and so forth. Having the rule target attributes containing at least one non-ASCII whitespace character ensures that there is at least one token in the set.

Bibliography

Test Cases

Passed

Passed Example 1

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This role attribute contains one token, and this token is a valid WAI-ARIA role.

<label>Search: <input type="text" role="searchbox" placeholder="Enter 3 or more characters"/></label>

Passed Example 2

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This role attribute contains two tokens, and these tokens are both valid WAI-ARIA roles.

<style>
	.ref {
		color: #0000ee;
		text-decoration: underline;
		cursor: pointer;
	}
</style>
See [<span class="ref" onclick="location.href='https://act-rules.github.io/'" role="doc-biblioref link">ACT rules</span
>].

Passed Example 3

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This role attribute contains two tokens, and one of these tokens (searchbox) is a valid WAI-ARIA role.

<label>Search: <input type="text" role="searchfield searchbox" placeholder="Enter 3 or more characters"/></label>

Failed

Failed Example 1

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This role attribute contains one token, but this token is not a valid role in any of the WAI-ARIA specifications.

<style>
	.link {
		color: #0000ee;
		text-decoration: underline;
		cursor: pointer;
	}
</style>
I love <span class="link" onclick="location.href='https://act-rules.github.io/'" role="lnik">ACT rules</span>.

Failed Example 2

Open in a new tab

This role attribute contains two tokens, but none of these tokens is a valid role in any of the WAI-ARIA specifications.

<style>
	.ref {
		color: #0000ee;
		text-decoration: underline;
		cursor: pointer;
	}
</style>
See [<span class="ref" onclick="location.href='https://act-rules.github.io/'" role="bibliographic-reference lnik"
	>ACT rules</span
>].

Inapplicable

Inapplicable Example 1

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There is no role attribute.

<img src="/test-assets/shared/w3c-logo.png" alt="W3C logo" />

Inapplicable Example 2

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This role attribute has no value.

<div role>Some Content</div>

Inapplicable Example 3

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This role attribute is empty ("").

<div role="">Some Content</div>

Inapplicable Example 4

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This role attribute is only ASCII whitespace.

<input type="text" role=" " />

Inapplicable Example 5

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This role attribute is specified on an element which is programmatically hidden.

<div aria-hidden="true" role="banner">Some Content</div>

Glossary

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.

Accessibility Support for Explicit Semantic Role

Some browsers and assistive technologies treat the tokens of the role attribute as case-sensitive. Unless lowercase letters are used for the value of the role attribute, not all user agents will be able to interpret the tokens correctly. ARIA in HTML (working draft) also specifies that authors must use lowercase letters for the role and aria-* attributes.

Focusable

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

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).

Accessibility Support for Implicit Semantic Role

  • Images with an empty alt attribute should have an implicit role of presentation, according to the HTML Accessibility API Mapping (work in progress). However, there are several popular browsers that do not treat images with empty alt attribute as having a role of presentation. Instead, they add the img element to the accessibility tree with a role of either img or graphic.

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.

Accessibility Support for Definition of Semantic Role for Semantic Role

  • There exist popular web browsers and assistive technologies which do not correctly implement Presentational Roles Conflict Resolution. These technologies will not include in the accessibility tree elements that should be, according to Specifications. Thus, some elements that should have their semantic role fixed by case Conflict above are instead falling into case Explicit and are hidden for users of assistive technologies.
  • A similar conflict exists for focusable elements with a aria-hidden="true" attribute. The WAI ARIA specification does not explain how to solve it. Some browsers give precedence to the element being focusable (and expose it in the accessibility tree) while some give precedence to the aria-hidden attribute (and hide the element).

Whitespace

Whitespace are characters that have the Unicode "White_Space" property in the Unicode properties list.

This includes:

  • all characters in the Unicode Separator categories, and

  • the following characters in the Other, Control category:

    • Character tabulation (U+0009)
    • Line Feed (LF) (U+000A)
    • Line Tabulation (U+000B)
    • Form Feed (FF) (U+000C)
    • Carriage Return (CR) (U+000D)
    • Next Line (NEL) (U+0085)

Useful Links

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. This section will not be included in the rule when it is published on the W3C website.

ToolConsistencyCompleteReport
Equal Access Accessibility CheckerconsistentYesView Report
QualWebconsistentYesView Report
SortSiteconsistentYesView Report

Acknowledgments

Authors

Funding

  • WAI-Tools
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