Audit duplicate-id-aria
Ensure every id attribute value used in ARIA and in labels is unique
Impact:
WCAG-Konformität:
- AWCAG 4.1.2
Issue type:
needs reviewId attribute value is unique
This rule checks that all `id` attribute values on a single page are unique.
Applicability
This rule applies to any id
attribute whose value is not an empty string (""
), specified on a HTML or SVG element.
Note: Elements that are neither included in the accessibility tree nor visible are still considered for this rule.
Expectation
The value of the attribute is unique across all other id
attributes specified on HTML or SVG elements that exist within the same document tree or shadow tree as the element on which the applicable id
attribute is specified.
Background
Assumptions
There are no assumptions.
Accessibility Support
There are no accessibility support issues known.
Bibliography
- Understanding Success Criterion 4.1.1: Parsing
- H93: Ensuring that id attributes are unique on a Web page
Test Cases
Passed
Passed Example 1
There is only one id
attribute within the document context.
<div id="my-div">This is my first element</div>
Passed Example 2
All id
attributes are unique within the document context.
<div id="my-div1">This is my first element</div>
<div id="my-div2">This is my second element</div>
<svg id="my-div3">This is my third element</svg>
Passed Example 3
Two of the id
attributes are the same (my-elt
), but they are in different trees (the first one in the document tree and the second in the shadow tree).
<div id="my-elt"></div>
<div id="host"></div>
<script>
var host = document.getElementById('host')
var shadow = host.attachShadow({ mode: 'open' })
shadow.innerHTML = '<b id="my-elt"></b>'
</script>
Passed Example 4
Both id
attributes are the same (my-elt
), but they are in different document trees because the iframe
is creating a new one.
<div id="my-elt"></div>
<iframe title="Empty frame" srcdoc="<span id='my-elt'></span>"></iframe>
Failed
Failed Example 1
The id
attribute label
is not unique among all id
attributes in the document, resulting in a wrong programmatic label on the input field.
<div id="label">Name</div>
<div id="label">City</div>
<input aria-labelledby="label" type="text" name="city" />
Failed Example 2
The id
attribute label
is not unique among all id
attributes in the document, resulting in a wrong programmatic label on the input field.
<div id="label">Name</div>
<svg id="label">
<text x="0" y="15">City</text>
</svg>
<input aria-labelledby="label" type="text" name="city" />
Failed Example 3
The id
attribute label
is not unique among all id
attributes in the document, resulting in a wrong programmatic label on the input field. This rule still considers elements that are neither included in the accessibility tree nor visible.
<span id="label" style="display: none;">Name</span>
<span id="label">City</span>
<input aria-labelledby="label" type="text" name="city" />
Inapplicable
Inapplicable Example 1
There is no id
attribute in this document.
<div>This is my first element</div>
Inapplicable Example 2
The xml:id
attribute is not considered by this rule.
<div xml:id="my-div">This is my first element</div>
Inapplicable Example 3
These id
attributes have an empty value.
<span id="">Hello</span> <span id="">world!</span>
Autoren: Anne Thyme Nørregaard, Bryn Anderson
Finanzierung: WAI-Tools