Proposed Object element rendering non-text content has non-empty accessible name
Description
This rule checks that each object
element rendering non-text content has a non-empty accessible name.
Applicability
This rule applies to any object
element for which all the following are true:
- The
object
element is included in the accessibility tree; and - The
object
element has no explicit role; and - The
object
element embeds a resource whose MIME type is either image, or audio or video.
Expectation
Each target element has an accessible name that is not empty (""
).
Assumptions
The object
element is not rendered for presentational purposes. If the object
is decorative and not marked as decorative then the rule might fail but the success criterion might still be satisfied.
Accessibility Support
The MIME type of the resource embedded in the data
attribute impacts how the accessible name of the object
is computed. For example, object
embedding image MIME type may use their alt
attribute to compute their accessible name, but object
embedding audio or video MIME types may not. An object
does not officially support the use of an alt
so this may behave differently according to the browser used.
Background
Testing that the accessible name describes the purpose of the object
element is not part of this rule and must be tested separately.
Non-supported media formats make screen readers render the text content of the element instead of other attributes.
Object
elements without an accessible name are ignored by assistive technologies unless they have an explicit role.
When the object resource is not loaded, the fallback content is rendered as shown in the Inapplicable Example: “This object
element does not need an accessible name because it loads no image, audio, or video.”
Bibliography
Accessibility Requirements Mapping
1.1.1 Non-text Content (Level A)
- Learn more about 1.1.1 Non-text Content
- 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
- Any
Input Aspects
The following aspects are required in using this rule.
Test Cases
Passed
Passed Example 1
This object
element which embeds an audio resource has a non-empty accessible name through its aria-label
attribute.
<object aria-label="Moon speech" data="/test-assets/moon-audio/moon-speech.mp3"></object>
Passed Example 2
This object
element which embeds a video resource has a non-empty accessible name through its title
attribute.
<object title="Rabbit animated short" data="/test-assets/rabbit-video/video.mp4"></object>
Passed Example 3
This object
element which embeds an image resource has a non-empty accessible name through its aria-labelledby
attribute.
<span id="label">W3C logo</span> <object aria-labelledby="label" data="/test-assets/shared/w3c-logo.png"></object>
Passed Example 4
This object
element placed off screen, which embeds an audio resource, has a non-empty accessible name through its title
attribute.
<html>
<style>
.offScreen {
position: absolute;
left: -9999px;
top: -9999px;
}
</style>
<body>
<object title="Moon speech" data="/test-assets/moon-audio/moon-speech.mp3" class="offScreen"></object>
</body>
</html>
Failed
Failed Example 1
This object
element which embeds an audio resource has an empty accessible name because it does not provide an accessible name through one of title
, aria-label
or aria-labelledby
attributes.
<object data="/test-assets/moon-audio/moon-speech.mp3"></object>
Failed Example 2
This object
element which embeds a video resource has an empty accessible name because the title
attribute is empty.
<object title="" data="/test-assets/rabbit-video/video.mp4"></object>
Failed Example 3
This object
element which embeds an image resource has an empty accessible name because the span
element with id="label"
is empty.
<span id="label"></span> <object aria-labelledby="label" data="/test-assets/shared/w3c-logo.png"></object>
Failed Example 4
This object
element which embeds an audio resource has an empty accessible name because the aria-labelledby
attribute references a non-existing id.
<object aria-labelledby="download" data="/test-assets/moon-audio/moon-speech.mp3"></object>
Failed Example 5
This object
element has an empty accessible name. The img
element inside the object
is not used in computing the object
’s accessible name.
<object data="/test-assets/shared/w3c-logo.png">
<img src="/test-assets/shared/w3c-logo.png" alt="W3C logo" />
</object>
Failed Example 6
This object
element has alt
attribute, however this will not create an accessible name. Because of this the accessible name is empty.
<object data="/test-assets/moon-audio/moon-speech.mp3" alt="Moon speech"></object>
Inapplicable
Inapplicable Example 1
This object
element has an explicit role of “img”.
Note: Object elements with other roles may still require an accessible name. This is tested through other rules.
<object role="img" title="W3C" data="/test-assets/shared/w3c-logo.png"></object>
Inapplicable Example 2
This object
element is not included in the accessibility tree due to display:none
.
<object data="/test-assets/rabbit-video/video.mp4" style="display: none;"></object>
Inapplicable Example 3
This object
element is not included in the accessibility tree due to visibility:hidden
.
<object data="/test-assets/moon-audio/moon-speech.mp3" style="visibility: hidden;"></object>
Inapplicable Example 4
This object
element is not included in the accessibility tree due to aria-hidden="true"
.
<object data="/test-assets/shared/w3c-logo.png" aria-hidden="true"></object>
Inapplicable Example 5
This object
element is not included in the accessibility tree because it is marked as decorative through role="presentation"
.
<object type="image/png" role="presentation" data="/test-assets/contrast/example.png"></object>
Inapplicable Example 6
This object
element embeds an HTML resource.
<object title="My University" data="/test-assets/shared/index.html"></object>
Inapplicable Example 7
There is no object
element.
<audio title="Moon speech" src="/test-assets/moon-audio/moon-speech.mp3"></audio>
Inapplicable Example 8
This object
element does not need an accessible name because it loads no image, audio, or video. Instead the img
element inside the object
is rendered.
<object data="/invalid/url/index.html">
<img src="/test-assets/shared/w3c-logo.png" alt="W3C logo" />
</object>
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.
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
orpresentation
; or - it is an
img
element with analt
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.
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
ofnone
; or - has an
aria-hidden
attribute 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.
WAI-ARIA specifications
The WAI ARIA Specifications group both the WAI ARIA W3C Recommendation and ARIA modules, namely:
- Accessible Rich Internet Applications (WAI-ARIA) 1.1
- 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.