Pointer Cancellation
Functions triggered by single-pointer activation must use the up-event (mouseup / touchend), allow abortion before completion, and not commit on the down-event alone.
What it requires
WCAG 2.5.2 protects users who tap or click incorrectly — they need a way to cancel before the action commits. The standard is: action commits on up-event (release), with the user able to drag pointer away to abort.
Onmousedown handlers that immediately commit are the canonical violation. Standard `<button onclick>` patterns satisfy the criterion automatically because click is fundamentally an up-event.
Common Shopify failure
Custom drag-to-delete cart-line component that commits the delete on touchstart instead of touchend, giving users no chance to cancel. Custom radio-swatch picker that commits on touchstart.
How to fix it
AccessComply rewrites onmousedown / ontouchstart handlers that commit immediately to use the up-event pattern with cancellation support.
Primary source: W3C — WCAG 2.1 Understanding 2.5.2