HTML page has lang attribute
Description
This rule checks that an HTML page has a non-empty lang attribute.
Applicability
This rule applies to any document element if it is an html element for which all the following are true:
- is in a top-level browsing context; and
- has a node document with a content type of
text/html.
Note: 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.
Expectation
Each test target has a lang attribute value that is neither empty ("") nor only ASCII whitespace.
Assumptions
The language of the page can be set by other methods than the lang attribute, for example using HTTP headers or the meta element. These methods are not supported by all assistive technologies. This rule assumes that these other methods are insufficient to satisfying Success Criterion 3.1.1: Language of Page.
Accessibility Support
There are no major accessibility support issues known for this rule.
Background
Related rules
Bibliography
- Understanding Success Criterion 3.1.1: Language of Page
- H57: Using language attributes on the html element
- RFC 5646: Tags for Identifying Languages
- The
langandxml:langattributes
Accessibility Requirements Mapping
3.1.1 Language of Page (Level A)
- Learn more about 3.1.1 Language of Page
- Required for conformance to WCAG 2.0 and later on level A and higher.
- Outcome mapping:
- Any
failedoutcomes: success criterion is not satisfied - All
passedoutcomes: success criterion needs further testing - An
inapplicableoutcome: success criterion needs further testing
- Any
H57: Using language attributes on the html element
- Learn more about technique H57
- Not required for conformance to any W3C accessibility recommendation.
- Outcome mapping:
- Any
failedoutcomes: technique is not satisfied - All
passedoutcomes: technique needs further testing - An
inapplicableoutcome: technique needs further testing
- Any
Input Aspects
The following aspects are required in using this rule.
Test Cases
Passed
Passed Example 1
This html element has a lang attribute with a non-empty ("") value.
<html lang="en"></html>
Failed
Failed Example 1
This html element does not have a lang attribute.
<html></html>
Failed Example 2
This html element has a lang attribute with an empty ("") value.
<html lang=""></html>
Failed Example 3
This html element has a lang attribute whose value is only ASCII whitespace.
<html lang=" "></html>
Failed Example 4
This html element has no lang attribute, only a xml:lang attribute.
<html xml:lang="en"></html>
Inapplicable
Inapplicable Example 1
This rule does not apply to an svg element.
<svg xmlns="http://www.w3.org/2000/svg"></svg>
Inapplicable Example 2
This rule does not apply to a math element.
<math></math>
Glossary
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 eitherImage Button(the state) orimage(the keyword mapping to it), both formulations having the same meaning; similarly, “an input element with atypeattribute value ofText” can be either<input type="text" />,<input />(missing value default), or<input type="invalid" />(invalid value default). - For boolean attributes, the attribute value is
truewhen the attribute is present andfalseotherwise. Thus<button disabled>,<button disabled="disabled">and<button disabled="">all have adisabledattribute value oftrue. - 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 and the HTML Accessibility API Mappings.
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.
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.
Rule Versions
-
Latest version, 31 August 2023
(compare)
- Add text of the correct language to each example.
- Previous version, 28 January 2022