Button has non-empty accessible name

  • Rule Type:atomic
  • Rule Id: 97a4e1
  • Last modified: Oct 23, 2020
  • Accessibility Requirements Mapping:
    • 4.1.2 Name, Role, Value (Level A)
      • Learn More about 4.1.2 Name, Role, Value
      • 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.

Description

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

Applicability

The rule applies to elements that are included in the accessibility tree and have a semantic role of button, except for input elements with a type attribute value of image.

Expectation

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

Note: input elements with a type attribute value of either submit or reset can get their accessible name from a default text, as well as from a value or other attribute.

Assumptions

Accessibility Support

  • Implementation of Presentational Roles Conflict Resolution varies from one browser or assistive technology to another. Depending on this, some elements can have a semantic role of button and fail this rule with some technology but users of other technologies would not experience any accessibility issue.

Background

Test Cases

Passed

Passed Example 1

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This button element has an accessible name because of its text content.

<button>My button</button>

Passed Example 2

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This input element has an accessible name because of its value attribute.

<input type="submit" value="Submit" />

Passed Example 3

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This button element has an accessible name because of its aria-label attribute.

<button aria-label="My button"></button>

Passed Example 4

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This element with a button role has an accessible name because of its aria-label attribute.

<span role="button" aria-label="My button"></span>

Passed Example 5

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This button element with the disabled attribute has an accessible name because of its text content.

<button disabled>Delete</button>

Passed Example 6

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This off screen button element has an accessible name because of its text content.

<html>
	<style>
		.notInPage {
			position: absolute;
			left: -9999px;
			top: -9999px;
		}
	</style>
	<body>
		<button class="notInPage">Save</button>
	</body>
</html>

Passed Example 7

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This input element has an accessible name because of the default accessible name for an input element with a type attribute set to reset.

<input type="reset" />

Failed

Failed Example 1

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This button element has no accessible name because it has no content or attribute that can provide it.

<button></button>

Failed Example 2

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This button element has no accessible name. The value attribute does not provide an accessible name for button elements, only when an input element's state of the type attribute is button, submit or reset.

<button type="button" value="read more"></button>

Failed Example 3

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This element with the button role has no accessible name because it has no content or attribute that can provide it.

<span role="button"></span>

Failed Example 4

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This off screen button element has no accessible name because it has no content or attribute that can provide it.

<html>
	<style>
		.notInPage {
			position: absolute;
			left: -9999px;
			top: -9999px;
		}
	</style>
	<body>
		<button class="notInPage" value="delete"></button>
	</body>
</html>

Failed Example 5

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This button element has an explicit role of none. However, it is focusable (by default). Thus it has a semantic role of button due to Presentational Roles Conflict Resolution. It has an empty accessible name.

<button role="none"></button>

Inapplicable

Inapplicable Example 1

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This input element has a type attribute set to image. These images are tested in a separate rule which also tests success criterion 1.1.1 Non-text Content.

<input type="image" value="download" alt="Download" />

Inapplicable Example 2

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This button element does not need an accessible name because it is not included in the accessibility tree.

<button style="display: none;"></button>

Inapplicable Example 3

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This button element has a link role. Links are tested in a separate rule which also tests success criterion 2.4.4 Link Purpose (In Context).

<button role="link">take me somewhere</button>

Inapplicable Example 4

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There is no element with a semantic role of button.

<div>Press Here</div>

Inapplicable Example 5

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This button element has an explicit role of none; it is not focusable because it is disabled. Thus it has a semantic role of none.

<button role="none" disabled></button>

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.

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 ("").
  • The accessible name and description computation suggest that if an aria-labelledby attribute 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.

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

  • For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, "an input element with a type attribute value of Text" can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
  • For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
  • For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
  • For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
  • For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
  • For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

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.

Accessibility Support for Explicit Semantic Role

Some browsers and assistive technologies treat the tokens of the role attribute as case-sensitive. Unless lowercase letters are used for the value of the role attribute, not all user agents will be able to interpret the tokens correctly. ARIA in HTML (working draft) also specifies that authors must use lowercase letters for the role and aria-* attributes.

Hidden State

An HTML element's hidden state is "true" if at least one of the following is true for itself or any of its ancestors in the flat tree:

  • has a hidden attribute; or
  • has a computed CSS property display of none; or
  • has a computed CSS property visibility of hidden; or
  • has an aria-hidden attribute set to true

In any other case, the element's hidden state is "false".

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).

Accessibility Support for Implicit Semantic Role

  • Images with an empty alt attribute should have an implicit role of presentation, according to the HTML Accessibility API Mapping (work in progress). However, there are several popular browsers that do not treat images with empty alt attribute as having a role of presentation. Instead, they add the img element to the accessibility tree with a role of either img or graphic.

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).

For more details, see examples of included in the accessibility tree.

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

Marked as decorative

An element is marked as decorative if one of the following conditions is true:

  • it has an explicit role of none or presentation; or
  • it is an img element with an alt 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 their hidden state is true. This is different from marking the element as decorative and does not convey the same intention. Notably, the hidden state of an element 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.

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 its hidden state is false, 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.

Accessibility Support for Definition of Semantic Role for Semantic Role

  • There exist popular web browsers and assistive technologies which do not correctly implement Presentational Roles Conflict Resolution. These technologies will not include in the accessibility tree elements that should be, according to Specifications. Thus, some elements that should have their semantic role fixed by case Conflict above are instead falling into case Explicit and are hidden for users of assistive technologies.
  • A similar conflict exists for focusable elements with a aria-hidden="true" attribute. The WAI ARIA specification does not explain how to solve it. Some browsers give precedence to the element being focusable (and expose it in the accessibility tree) while some give precedence to the aria-hidden attribute (and hide the element).

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.

ToolConsistencyCompleteReport
AlfaconsistentYesView Report
axe-coreconsistentYesView Report
QualWebconsistentYesView Report
SortSiteconsistentYesView Report
Access EngineconsistentNoView Report

Acknowledgments

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