SIA-R4`<html>` document elements have a `lang` attribute

Accessibility requirements

This rule tests conformance of the following accessibility requirements:

This rule checks that document elements have a lang attribute.

This rule applies to every document element if it is an <html> element in the HTML namespace that:

The element has a lang attribute with a value that is neither empty nor only ASCII whitespace.

This rule makes the following assumption:

The lang attribute is being used to conform to WCAG. As such, this rule doesn't test if the attribute is needed to conform to WCAG.

This rule has the following accessibility support concern:

<html> elements within <iframe> and <object> elements are not applicable as <iframe> and <object> elements create nested browsing contexts. However, as these elements are meant to provide a layer of isolation, the declared language of their parent browsing context will likely not be inherited, making it possible for empty lang attributes in nested browsing contexts to also cause accessibility issues.

This <html> element has a lang attribute that is neither empty nor only ASCII whitespace and therefore passes the rule:

<html lang="en"></html>

This <html> element has no lang attribute and therefore fails the rule:

<html></html>

This <html> element has a lang attribute with a value that is empty and therefore fails the rule:

<html lang=""></html>

This <html> element has a lang attribute with a value that is only ASCII whitespace and therefore fails the rule:

<html lang=" "></html>

This document element is not an <html> element and is therefore inapplicable:

<svg xmlns="http://www.w3.org/2000/svg" lang="en"></svg>