Proposed Heading has non-empty accessible name
Description
This rule checks that each heading has a non-empty accessible name.
Applicability
This rule applies to any HTML element that is a semantic heading, included in the accessibility tree.
Expectation
Each test target has a non-empty ("") accessible name.
Assumptions
There are no assumptions.
Accessibility Support
-
Some assistive technologies may hide headings with empty accessible name from the users. This depends on the user agent, on how the accessible name was computed (the accessible name and description computation is not clear concerning which characters should be trimmed), and on the assistive technology itself. Hence, there are cases where the outcome of this rule is failed, but users of certain assistive technology and browser combinations will not experience an issue.
-
Implementation of Presentational Roles Conflict Resolution varies from one browser or assistive technology to another. Depending on this, some semantic
headingelements can fail this rule with some technology but users of other technologies would not experience any accessibility issue because the same elements would have a semantic role ofpresentationand be hidden for these users. -
The accessible name and description computation suggests that if an
aria-labelledbyattribute refers to an existing but empty element, the computation should stop and return an empty name without defaulting to the next steps. Several user agents and assistive technologies chose to use the next step in the computation in this case (ultimately defaulting to the content).
Background
Completely empty headings (e.g., <h1></h1>) seem to be consistently ignored by assistive technologies. However, they fail Technique H42: Using h1-h6 to identify headings (by using heading markup for content which is not heading). Moreover, they may be rendered on screen (by breaking flow content, or because of custom styling), thus causing concerns for sighted users. Therefore, this rule also fails on these.
Bibliography
- Understanding Success Criterion 1.3.1: Info and Relationships
- Technique H42: Using h1-h6 to identify headings
Accessibility Requirements Mapping
- This rule is not required for conformance to WCAG 2.1 at any level.
Input Aspects
The following aspects are required in using this rule.
Test Cases
Passed
Passed Example 1
This h1 element has a non-empty accessible name.
<h1>ACT rules</h1>
Passed Example 2
This div element with a semantic role of heading has a non-empty accessible name.
<div role="heading" aria-level="1">ACT rules</div>
Passed Example 3
This h1 element has a non-empty accessible name given by its aria-labelledby attribute.
<span id="h-name" hidden>ACT rules</span>
<h1 aria-labelledby="h-name">Learn about ACT rules</h1>
Passed Example 4
This h1 element has a non-empty accessible name given by the alt attribute of its content.
<h1><img src="/test-assets/shared/act-logo.png" alt="ACT rules" /></h1>
Passed Example 5
This h1 element is not visible, but is still included in the accessibility tree. It has a non-empty accessible name.
<h1 style="position: absolute; top: -9999px">ACT rules</h1>
Failed
Failed Example 1
This h1 element has an empty accessible name because its content is not exposed to assistive technologies.
<h1><img src="/test-assets/shared/act-logo.png" alt="" /></h1>
Failed Example 2
This h1 element has an empty accessible name given by its aria-label attribute. Its content is not exposed to assistive technologies, thus preventing the accessible name to default to the content.
<h1 aria-label=""><span aria-hidden="true">ACT rules</span></h1>
Failed Example 3
This h1 element has an empty accessible name given by its aria-labelledby attribute. Its content is not exposed to assistive technologies, thus preventing the accessible name to default to the content.
<span id="h-name" hidden></span>
<h1 aria-labelledby="h-name"><span aria-hidden="true">ACT rules</span></h1>
Failed Example 4
This h1 element has an empty accessible name because the img element has a semantic role of presentation, and thus does not provide an accessible name to the h1 element. Note that the alt attribute does not trigger Presentational Roles Conflict Resolution because it is not an ARIA attribute.
<h1><img src="/test-assets/shared/act-logo.png" alt="ACT rules" role="presentation" /></h1>
Failed Example 5
This h1 element has an empty accessible name because the spaces and line break are trimmed by accessible name computation.
<h1><br /></h1>
Failed Example 6
This h1 element has an empty accessible name. It is nonetheless rendered by breaking the flow content, resulting in a confusing situation for sighted users.
<span>Hello</span>
<h1></h1>
<span>World!</span>
Failed Example 7
This div element with a semantic role of heading has an empty accessible name (and content). It is nonetheless rendered due to its styling, resulting in a confusing situation for sighted users.
<div role="heading" aria-level="1" style="border-style: solid"></div>
Failed Example 8
This h1 element has an explicit role of none. However, the global property aria-label is specified. Thus it has a semantic role of heading due to Presentational Roles Conflict Resolution. It has an empty accessible name given by its aria-label attribute and the lack of accessible content to fallback to.
<h1 aria-label="" role="none"><span aria-hidden="true">ACT rules</span></h1>
Inapplicable
Inapplicable Example 1
There is no semantic heading element.
<div></div>
Inapplicable Example 2
This h1 element is not included in the accessibility tree.
<h1 aria-hidden="true"></h1>
Glossary
Accessible Name
The accessible name is the programmatically determined name of a user interface element that is included in the accessibility tree.
The accessible name is calculated using the accessible name and description computation.
For native markup languages, such as HTML and SVG, additional information on how to calculate the accessible name can be found in HTML Accessibility API Mappings 1.0, Accessible Name and Description Computation (working draft) and SVG Accessibility API Mappings, Name and Description (working draft).
For more details, see examples of accessible name.
Note: As per the accessible name and description computation, each element always has an accessible name. When no accessible name is provided, the element will nonetheless be assigned an empty ("") one.
Note: As per the accessible name and description computation, accessible names are flat string trimmed of leading and trailing whitespace. Notably, it is not possible for a non-empty accessible name to be composed only of whitespace since these must be trimmed.
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
noneorpresentation; or - it is an
imgelement with analtattribute 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
displayofnone; or - has an
aria-hiddenattribute set totrue
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:
- 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.
- Explicit If the element has an explicit role, then its semantic role is its explicit role.
- 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.
Visible
Content perceivable through sight.
Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.
For more details, see examples of visible.
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 | Partial |  |
| Alfa (semi-automated) 0.80.0 | Semi-automated tool | Partial | |
| Axe DevTools Pro 4.37.1 | Semi-automated tool | Consistent | |
| Axe-core 4.8.3 | 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 | |