Keyboard Trap

Property	Value
ID	keyboard-trap
Severity	Error
WCAG	2.1.2 No Keyboard Trap
Config	keyboardTrap

What it checks

Detects evidence that forward Tab navigation is stuck or does not cycle. Keylens does not run a separate Shift+Tab escape test.

How it works

1. Consecutive duplicate detection: If the same element selector appears consecutively in the focus sequence, focus is likely trapped.
2. Incomplete cycle warning: If the tab cycle never returns to the first element within maxTabs attempts, a warning is raised. Large or changing pages and timed-out Tab presses can also cause this warning.

Examples

Fail

<!-- JavaScript prevents Tab from moving focus away -->
<div role="combobox" onkeydown="event.preventDefault()">Search...</div>

Pass

<!-- Tab moves focus normally -->
<input type="search" placeholder="Search..." />

How to fix

• Ensure all keydown handlers allow Tab and Shift+Tab to pass through
• For modal dialogs, trap focus within the dialog but allow Escape to close it
• Avoid calling event.preventDefault() on Tab key events