guideline: Predictable
Make sure websites and apps behave in consistent and expected ways, so people aren’t surprised or confused by unexpected changes.
WCAG 2.0, 2.1, 2.2
Level A
3.2.1 On Focus
No unexpected changes must happen when an element receives focus (like open a popup, move focus, submit a form).
WCAG 2.0, 2.1, 2.2
Level A
3.2.2 On Input
No unexpected changes must happen when a field value changes (like auto-submit, reload, open new page).
WCAG 2.0, 2.1, 2.2
Level AA
3.2.3 Consistent Navigation
Navigation elements (like menus, links, search) must appear in the same place and order across pages.
WCAG 2.0, 2.1, 2.2
Level AA
3.2.4 Consistent Identification
Elements with the same function must look, behave, and be labeled the same way across pages.
WCAG 2.0, 2.1, 2.2
Level AAA
3.2.5 Change on Request
Major changes (like open dialog, navigate, submit) must only happen when explicitly requested.
WCAG 2.2
Level A
3.2.6 Consistent Help
Help options (like contact link, support widget) must appear in the same place across pages.