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Proposed Element with role attribute has required states and properties

Description

This rule checks that elements that have an explicit role also specify all required states and properties.

Applicability

This rule applies to any HTML or SVG element that is included in the accessibility tree and 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.

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

Omitting WAI-ARIA required states and properties is often the result of a developer error. When required properties are missing and a default value is not specified by WAI-ARIA Specifications, the behavior is not defined. For WAI-ARIA 1.2, the only explicit semantic roles with a required property with a default value are the option and tabs roles for the aria-selected property.

This rule is testing author built components that specify explicit semantic roles and not components that keep their implicit semantic role. For components that keep their implicit semantic role, all native HTML and SVG elements have native attributes that are mapped to all of the WAI-ARIA required states and properties. Most of these mappings are defined in the HTML Accessibility API Mappings, Attribute State and Property Mappings.

Bibliography

Accessibility Requirements Mapping

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:

Input Aspects

The following aspects are required in using this rule.

Test Cases

Passed

Passed Example 1

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This heading has the required aria-level property.

<div role="heading" aria-level="1">
	My First Heading
</div>

Passed Example 2

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This checkbox has the required aria-checked property.

<div role="checkbox" aria-checked="false"></div>
<div id="label">Check me</div>

Passed Example 3

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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 4

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These option nodes do not need the required aria-selected property because it has a default value of false.

<div id="label">Tags</div>
<ul role="listbox" aria-labelledby="label">
	<li role="option">Zebra</li>
	<li role="option">Zoom</li>
</ul>

Passed Example 5

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This separator is not a widget because it is not focusable. The separator role only requires the aria-valuenow property when the element is focusable.

<p>My first HTML</p>
<div role="separator"></div>
<p>My last HTML</p>

Passed Example 6

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This combobox has the required properties aria-controls and aria-expanded.

<label for="tag_combo">Tag</label>
<input type="text" id="tag_combo" role="combobox" aria-expanded="true" aria-controls="popup_listbox" />
<ul role="listbox" id="popup_listbox">
	<li role="option">Zebra</li>
	<li role="option" id="selected_option">Zoom</li>
</ul>

Failed

Failed Example 1

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This heading does not have the required aria-level property. Prior to WAI-ARIA 1.2 the heading role had an implicit default aria-level value of 2. As of WAI-ARIA 1.2 this property must be explicitly set.

<div role="heading">
	My First Heading
</div>

Failed Example 2

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This switch does not have the required aria-checked property. Prior to WAI-ARIA 1.2 the switch role had an implicit default aria-checked value of false. As of WAI-ARIA 1.2 this property must be explicitly set.

<div role="switch">
	Toggle me
</div>

Failed Example 3

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This checkbox does not have the required property aria-checked. Prior to WAI-ARIA 1.2 the checkbox had an implicit default aria-checked value of false. As of WAI-ARIA 1.2 this property must be explicitly set.

<div role="checkbox" aria-labelledby="label"></div>
<div id="label">Check me</div>

Failed Example 4

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This separator does not have the required aria-valuenow property. This is required because the separator is focusable, which makes it a widget.

<p>My first HTML</p>
<div role="separator" tabindex="0"></div>
<p>My last HTML</p>

Failed Example 5

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This combobox does not have the required aria-expanded property. Prior to WAI-ARIA 1.2 the combobox had an implicit default aria-expanded value of false. As of WAI-ARIA 1.2 this property must be explicitly set.

<label for="tag_combo">Tag</label>
<input type="text" id="tag_combo" role="combobox" aria-controls="popup_listbox" />
<ul role="listbox" id="popup_listbox">
	<li role="option">Zebra</li>
	<li role="option" id="selected_option">Zoom</li>
</ul>

Failed Example 6

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This combobox uses aria-owns instead of using the required aria-controls property.

<label for="tag_combo">Tag</label>
<input type="text" id="tag_combo" role="combobox" aria-expanded="true" aria-owns="popup_listbox" />
<ul role="listbox" id="popup_listbox">
	<li role="option">Zebra</li>
	<li role="option" id="selected_option">Zoom</li>
</ul>

Inapplicable

Inapplicable Example 1

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This div does not have a semantic role.

<div>Some Content</div>

Inapplicable Example 2

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This checkbox has an implicit semantic role that is identical to the explicit semantic role. This allows native HTML checked attribute to apply.

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

Inapplicable Example 3

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This combobox is not included in the accessibility tree due to its styling, hiding it from everybody.

<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.

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:

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:

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:

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:

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:

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) 0.57.2 Automated tool Consistent Alfa (fully automated) Report
Alfa (semi-automated) 0.57.2 Semi-automated tool Consistent Alfa (semi-automated) Report
Axe DevTools Pro 4.37.1 Semi-automated tool Consistent Axe DevTools Pro Report
Axe-core 4.8.3 Automated tool Consistent Axe-core Report
Equal Access Accessibility Checker 3.1.42-rc.0 Automated tool Consistent Equal Access Accessibility Checker Report
QualWeb 3.0.0 Automated tool Consistent QualWeb Report
SortSite 6.45 Automated tool Consistent SortSite Report
Total Validator 17.4.0 Linter Consistent Total Validator Report
Total Validator (+Browser) 17.4.0 Automated tool Consistent Total Validator (+Browser) Report
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