Element with role attribute has required states and properties

  • Rule Type:atomic
  • Rule Id: 4e8ab6
  • Last modified: May 20, 2020
  • Accessibility Requirements Mapping:
    • 4.1.2 Name, Role, Value (Level A)
      • Learn More about 4.1.2 Name, Role, Value
      • 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.
    • ARIA5: Using WAI-ARIA state and property attributes to expose the state of a user interface component
      • Learn More about technique ARIA5
      • 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 elements that have an explicit role also specify all required states and properties.

Applicability

Any HTML or SVG element that has an explicit semantic role, except if the element has an implicit semantic role that is identical to the explicit semantic role.

Expectation

For each test target, the WAI-ARIA required states and properties for the role are set and not empty (""), unless the state or property has a default value listed under WAI-ARIA implicit value for role.

Note: In WAI-ARIA 1.2, required states and properties will no longer have a default value.

Assumptions

Accessibility Support

This rule relies on browsers and assistive technologies to support leaving out WAI-ARIA required states and properties when a WAI-ARIA implicit value for role is specified in WAI-ARIA Specifications.

Note: The required states and properties with implicit values can be found in the Core Accessibility API Mappings 1.1 Overview of default values for missing required attributes.

Background

Test Cases

Passed

Passed Example 1

Open in a new tab

This checkbox has the required property aria-checked.

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

Passed Example 2

Open in a new tab

This scrollbar has the required properties aria-controls and aria-valuenow. aria-valuemin has a default value of 0 and aria-valuemax of 100.

<div role="scrollbar" aria-controls="content" aria-valuenow="0"></div>
<main id="content"></main>

Passed Example 3

Open in a new tab

This combobox has required properties aria-controls and aria-expanded. aria-controls references an element that does not exist, but may be added to the page when expanded.

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

Failed

Failed Example 1

Open in a new tab

This combobox is missing the required aria-controls property.

Note: In WAI-ARIA 1.2, combobox will also require aria-expanded.

<div role="combobox" aria-expanded="true"></div>

Failed Example 2

Open in a new tab

This combobox has an empty value for the required aria-controls property.

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

Inapplicable

Inapplicable Example 1

Open in a new tab

This div does not have a semantic role.

<div>Some Content</div>

Inapplicable Example 2

Open in a new tab

This checkbox has an implicit semantic role that is identical to the explicit semantic role.

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

Inapplicable Example 3

Open in a new tab

This combobox is hidden.

<div role="combobox" style="display:none;"></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.

Hidden State

An HTML element's hidden state is "true" if at least one of the following is true for itself or any of its ancestors in the flat tree:

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

In any other case, the element's hidden state is "false".

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. Elements in the accessibility tree are exposed to assistive technologies, allowing users to interact with the elements in a way that meet 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.

Note: Users of assistive technologies might still be able to interact with elements that are not included in the accessibility tree. An example of this is a focusable element with an aria-hidden attribute with a value of true. Such an element could still be interacted using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree.

Marked as decorative

An element is marked as decorative if one 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 their hidden state is true. This is different from marking the element as decorative and does not convey the same intention. Notably, the hidden state of an element 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.

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.

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 its hidden state is false, 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.

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).

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
AlfaconsistentYesView Report
QualWebconsistentYesView Report

Acknowledgments

Table of Contents