A11ying with Sanna - Web Content Accessibility Guidelines a guide to the accessibility requirements
3 Understandable

3.2.1 On Focus

Conformance level: A
Criterion released in WCAG version: 2.0

Official description of the success criterion

When any user interface component receives focus, it does not initiate a change of context.

What to do?

Ensure elements do not initiate a change of context when they receive focus.

Why is it important?

Prevents unexpected changes that can confuse users.

Common pitfalls

Opening context-changing elements when the component receives focus. Example: opening a new window.

More about this criterion elsewhere