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Element marked as decorative is not exposed

Description

This rule checks that elements marked as decorative either are not included in the accessibility tree, or have a presentational role.

Applicability

This rule applies to any element which is marked as decorative.

Expectation

Each target element either is not included in the accessibility tree or has a semantic role of none or presentation.

Assumptions

There are currently no assumptions

Accessibility Support

Implementation of the Presentational Roles Conflict Resolution differs slightly from one user agent to the other. Hence, some elements might be exposed by one user agent and not by another, and consequently might create accessibility issues only for some users. Nevertheless, triggering the conflict is a bad practice.

Background

Elements are normally marked as decorative to convey the intention of the author that they are pure decoration and thus shouldn’t be exposed to assistive technologies. On the other hand, elements that are focusable are important to know for anybody and should be exposed to assistive technologies; and elements that are defining any global ARIA attribute indicate an intention to communicate something to the assistive technologies (through the aria-* attribute). When an element is both marked as decorative and either focusable or defining a global ARIA attribute, a conflict arises between these two intentions. The conflict is resolved by exposing the element.

Whenever such a conflict occurs, this indicates at the very least mismatching intentions. Such a conflict should be avoided.

When these conflicts arise on decorative non-text content, this is also a failure of Success Criterion 1.1.1: Non-text Content because decorative non-text content must be implemented in a way that allows assistive technologies to ignore it. When these conflicts arise on text content, or on content which is not decorative, this is not a failure of WCAG. Therefore this rule is not mapping to any specific WCAG Success Criterion, and is not an accessibility requirement for WCAG.

Accessibility Requirements Mapping

This rule is not required for conformance.

Input Aspects

The following aspects are required in using this rule.

Test Cases

Passed

Passed Example 1

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This img element is marked as decorative through its empty alt attribute and has semantic role of none.

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

Passed Example 2

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This img element is marked as decorative through its empty alt attribute and is not included in the accessibility tree because of the aria-hidden attribute.

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

Passed Example 3

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This img element is marked as decorative through its empty alt attribute and is not included in the accessibility tree because it is hidden to everyone.

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

Passed Example 4

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This nav element is marked as decorative through its role attribute and has a semantic role of presentation.

<nav role="presentation">
	<a href="https://act-rules.github.io/" aria-label="ACT rules">ACT rules</a>
</nav>

Passed Example 5

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This img element is marked as decorative through its role attribute and has a semantic role of presentation because own attributes are not required to be exposed and thus do not trigger the presentational roles conflict resolution.

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

Passed Example 6

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This svg element is marked as decorative through its role attribute and has a semantic role of none.

<svg role="none">
	<circle cx="50" cy="50" r="40" fill="yellow"></circle>
</svg>

Failed

Failed Example 1

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This nav element is marked as decorative through its role attribute but has a non-empty aria-label attribute causing it to be included in the accessibility tree with its implicit role of navigation.

<nav role="presentation" aria-label="global">
	<a href="https://act-rules.github.io/" aria-label="ACT rules">ACT rules</a>
</nav>

Failed Example 2

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This img element is marked as decorative through its empty alt attribute but has a non-empty aria-labelledby attribute causing it to be included in the accessibility tree with its implicit role of img.

<img src="/test-assets/shared/w3c-logo.png" alt="" aria-labelledby="label" /> <span hidden id="label">W3C logo</span>

Failed Example 3

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This svg element is marked as decorative through its role attribute but has a non-empty aria-label attribute causing it to be included in the accessibility tree with its implicit role of graphics-document.

<svg role="none" aria-label="Yellow circle">
	<circle cx="50" cy="50" r="40" fill="yellow"></circle>
</svg>

Inapplicable

Inapplicable Example 1

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This img element is not marked as decorative.

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

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

Elements that can become the target of keyboard input as described in the HTML specification of focusable and can be focused.

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.

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

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.

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 Consistency Complete Report
Alfa Consistent Yes View Report
QualWeb Consistent Yes View Report
SortSite Consistent Yes View Report

Changelog

This is the first version of this ACT rule.

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This is an unpublished draft preview that might include content that is not yet approved. The published website is at w3.org/WAI/.