EA-R53
<iframe> has negative tabindex
This rule is an error and tests the following accessibility guidelines:
Description
This rule checks that iframe elements with a negative tabindex attribute value contain no interactive elements.
Explanation
<iframe> elements with a negative tabindex attribute must not contain interactive elements. By setting the tabindex attribute value of an iframe element to -1 or some other negative number, it becomes impossible to move the focus into the browsing context of the iframe element.
Expectation 1
For each test target, the nested browsing context does not contain elements that are visible and part of the sequential focus navigation.
Expectation 2
An element is contained in a nested browsing context if its owner document is the container document of the nested browsing context.
Assumptions
This rule assumes that interactive content inside iframe elements is used to provide functionality. If the interactive content does not provide functionality, for example a button that does nothing when clicked, success criterion 2.1.1 may be satisfied, even if the rule is failed.
Accessibility Support
There are no major accessibility support issues known for this rule.
Background
By setting the tabindex attribute value of an iframe element to -1 or some other negative number, it becomes impossible to move the focus into the browsing context of the iframe element. Even though its content is still included in the sequential focus navigation, there is no way to move the focus to any of the items in the iframe using standard keyboard navigation.
Tip
Remove the negative tabindex if the <iframe> contains focusable elements.
Examples
Passed
Example 1 - Passed
This iframe element contains no content that is part of sequential focus navigation.
Example 2 - Passed
This iframe element contains a link that is not part of sequential focus navigation because of its tabindex.
Example 3 - Passed
This iframe element contains no visible content because of the small size of the iframe.
Example 4 - Passed
This iframe element contains no visible content because the iframe is hidden.
Failed
Example 1 - Failed
This iframe element has a link that is part of sequential focus navigation.
Inapplicable
Example 1 - Inapplicable
This iframe element does not have a tabindex attribute value that is a negative number
Acknowledgments
This document includes material copied from or derived from https://www.w3.org/WAI/standards-guidelines/act/rules/4b1c6c/. Copyright © 2023 W3C® (MIT, ERCIM, Keio, Beihang).
