Image button has non-empty accessible name


Description

This rule checks that each image button element has a non-empty accessible name.

Applicability

The rule applies to any input element where the state of the type attribute is image, and that is included in the accessibility tree.

Expectation

Each target element has an accessible name that is not empty ("").

Assumptions

Accessibility Support

There is a known combination of a popular browser and assistive technology that does not by default support title as an accessible name.

Background

Test Cases

Passed

Passed Example 1

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The image button has an accessible name through the alt attribute.

<input type="image" src="/test-assets/shared/search-icon.svg" alt="Search" />

Passed Example 2

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The image button has an accessible name through the aria-label attribute.

<input type="image" src="/test-assets/shared/search-icon.svg" aria-label="Search" />

Passed Example 3

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The image button has an accessible name through the title attribute.

note: The title attribute may not always be accessibility supported.

<input type="image" src="/test-assets/shared/search-icon.svg" title="Search" />

Passed Example 4

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The image button has an accessible name through the aria-labelledby attribute.

<input type="image" src="/test-assets/shared/search-icon.svg" aria-labelledby="id1" />
<div id="id1">Search</div>

Failed

Failed Example 1

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The image button element has an empty accessible name. The name attribute can not be used to provide an accessible name.

<input type="image" name="search" src="/test-assets/shared/search-icon.svg" />

Failed Example 2

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The image button has an empty alt attribute, and no other attributes that can give it an accessible name.

<input type="image" src="/test-assets/shared/search-icon.svg" alt="" />

Failed Example 3

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The image button has an aria-labelledby attribute, but the referenced element does not exist. This gives the button an empty accessible name.

<input type="image" src="/test-assets/shared/search-icon.svg" aria-labelledby="non-existing" />

Inapplicable

Inapplicable Example 1

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The button element is not an image button. Success Criterion 1.1.1 Non-text Content can not fail text buttons. Only non-text content is applicable.

<button>My button</button>

Inapplicable Example 2

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The input element with type with a type attribute in the Button state is not an image button. Success Criterion 1.1.1 Non-text Content can not fail text buttons. Only non-text content is applicable.

<input type="button" value="My button" />

Inapplicable Example 3

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The button element is tested separately from the img element. Success Criterion 4.1.2 Name, Role, Value is applied to the button, whereas the image is tested under Success Criterion 1.1.1 Non-text Content

<button><img src="/test-assets/shared/search-icon.svg" alt="Search" /></button>

Inapplicable Example 4

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The img element is not a user interface component, and so is not tested for Success Criterion 4.1.2 Name, Role, Value.

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

Inapplicable Example 5

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The image button is ignored by assistive technologies because it is not included in the accessibility tree. These are not required to have an accessible name. If at some future state of the page the element gets included in the accessibility tree, an accessible name will be necessary.

<input type="image" src="/test-assets/shared/search-icon.svg" style="display: none;" />

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).

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.

Accessibility Support for Accessible Name

  • Because the accessible name and description computation is not clear about which whitespace are considered, browsers behave differently when trimming and flattening the accessible name. For example, some browsers completely trim non-breaking spaces while some keep them in the accessible name.
  • There exists a popular browser which does not perform the same trimming and flattening depending whether the accessible name comes from content, an aria-label attribute, or an alt attribute.
  • There exists a popular browser which assign no accessible name (null) when none is provided, instead of assigned an empty accessible name ("").

Examples for Accessible Name

Note: The examples presented here are non-normative and not testable. They serve to illustrate some common pitfalls about the definition and to help implementers of ACT rules understand it.

The input elements have an accessible name of, respectively, "Billing Name" and "Billing Address". These accessible names are given by the aria-labelledby attributes and associated elements.

<div id="myBillingId">Billing</div>

<div>
	<div id="myNameId">Name</div>
	<input type="text" aria-labelledby="myBillingId myNameId" />
</div>
<div>
	<div id="myAddressId">Address</div>
	<input type="text" aria-labelledby="myBillingId myAddressId" />
</div>

This button element has an accessible name of "Share ACT rules" given by its aria-label attribute.

<button aria-label="Share ACT rules">Share</button>

This img element has an accessible name of "ACT rules" given by its alt attribute.

<img src="#" alt="ACT rules" />

The button element has an accessible name of "Share ACT rules" given by the enclosing label element (implicit label)

<label>Share ACT rules<button>Share</button></label>

The button element has an accessible name of "Share ACT rules" given by the associated label element (explicit label)

<label for="act-rules">Share ACT rules</label><button id="act-rules"></button>

This a element has an accessible name of "ACT rules" given from its content. Note that not all semantic roles allow name from content.

<a href="https://act-rules.github.io/">ACT rules</a>

This span element has an empty accessible name ("") because span does not allow name from content.

<span>ACT rules</span>

This span element has an empty accessible name ("") because span is not a labelable element.

<label>ACT rules<span></span></label>

Note: When the same element can have an accessible name from several sources, the order of precedence is: aria-labelledby, aria-label, own attributes, label element, name from content. The examples here are listed in the same order.

Note: For more examples of accessible name computation, including many tricky cases, check the Accessible Name Testable Statements.

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).

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 with using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree.

Examples for Included in the accessibility tree

Note: The examples presented here are non-normative and not testable. They serve to illustrate some common pitfalls about the definition and to help implementers of ACT rules understand it.

This span element is included in the accessibility tree (by default, elements are included in the accessibility tree).

<span>ACT rules</span>

This span element is not included in the accessibility tree because it is hidden to everybody by the CSS property.

<span style="display:none">ACT rules</span>

This span element is not included in the accessibility tree because it is explicitly removed by the aria-hidden attribute.

<span aria-hidden="true">ACT rules</span>

This span element is positioned off screen, hence is not visible, but is nonetheless included in the accessibility tree.

<span style="position: absolute; top:-9999em">ACT rules</span>

Although the span element with an id of "label" is not itself included in the accessibility tree, it still provides an accessible name to the other span, via the aria-labelledby attribute. Thus, it is still indirectly exposed to users of assistive technologies. Removing an element from the accessibility tree is not enough to remove all accessibility concerns from it since it can still be indirectly exposed.

<span id="label" style="display:none">ACT rules</span>
<span aria-labelledby="label">Accessibility Conformance Testing rules</span>

Although this input element is not included in the accessibility tree, it is still focusable, hence users of assistive technologies can still interact with it by sequential keyboard navigation. This may result in confusing situations for such users (and is in direct violation of the fourth rule of ARIA (working draft)).

<input type="text" aria-hidden="true" name="fname" />

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.


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.

ToolConsitencyCompleteReport
AlfaconsistentYesView Report
axe-coreconsistentYesView Report
QualWebconsistentYesView Report
SortSiteconsistentYesView Report

Acknowledgments

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