SIA-R19`aria-*` states and properties have a valid value

Accessibility requirements

This rule tests conformance of the following accessibility requirements:

Description

This rule checks that ARIA states and properties have a valid value.

Applicability

This rule applies to every attribute with a value that is not empty (""), specified on an element included in the accessibility tree, where the name of the attribute corresponds to a WAI-ARIA state or property.

Expectations

The attribute has a value that is allowed by the value type of the corresponding state or property.

Additionally, if the attribute is required on the role of its owner, and the value type is ID reference or ID reference list, then the document tree or shadow tree of the owner of the target attribute contains at least one element whose ID matches one of the tokens in the value of the attribute.

Assumptions

This rule makes no assumptions.

Accessibility support

This rule has no known accessibility support concerns.

Examples

Passed

This aria-required property has a valid value according to its value type of true/false and therefore passes the rule:

<div role="textbox" aria-required="true" aria-label="A required textbox"></div>

Failed

This aria-required property does not have a valid value according to its value type of true/false and therefore fails the rule:

<div
    role="textbox"
    aria-required="undefined"
    aria-label="A required textbox"
></div>

This aria-controls property, which is a required property for the role scrollbar, references an element that does not exist in the same document tree.

<div
	role="scrollbar"
	aria-controls="content"
	aria-orientation="vertical"
	aria-valuemax="100"
	aria-valuemin="0"
	aria-valuenow="25"
></div>

Inapplicable

This element does not have any WAI-ARIA states or properties and is therefore inapplicable:

<div>Some Content</div>

Implementation details

While aria-controls is required on the role of combobox in ARIA 1.2, it is not anymore in ARIA 1.3 (unless the combobox is expanded), and the WAI-ARIA authoring practice for combobox only requires it on open comboboxes. Therefore, Alfa does not check the validity of ID ref list for aria-controls on a combobox.

SIA-R19aria-* states and properties have a valid value