HTML documents should have a valid IETF’s BCP 47 lang attribute.

Why is this an issue?

Screen readers require a specified language to function correctly. Without it, they default to the user’s set language, causing issues for multilingual users. Specifying a valid language ensures correct pronunciation and a less confusing experience.

How to fix it

Add a lang attribute with a valid IETF BCP 47 value.

Code examples

Noncompliant code example

Compliant solution

Resources

Documentation

• eslint-plugin-jsx-a11y - Rule lang
• eslint-plugin-jsx-a11y - Rule html-has-lang
• W3C, Language tags in HTML and XML