Slide to confirm

The ancestor is slide to unlock, which existed because a phone in a pocket is pressed constantly and a tap is the one thing a pocket can produce. That is the whole mechanism. A drag has a beginning, a direction, a distance and an end, and nothing bumps into all four of those by accident. Once the pattern was understood as a guard rather than as a lock screen it moved to the places where an accidental commit is expensive: payment terminals, industrial stops, ending a live broadcast, wiping a device. The label usually states the act (“slide to delete”), because a track that says nothing is a puzzle rather than a confirmation.

It has two published siblings on this site and choosing between them is a question of what you want the guard to cost. Hold to confirm charges time: a second of sustained pressure, cheap to learn, awkward for anyone whose hands do not hold still. Type to confirm charges attention and knowledge, since copying the name of the thing proves you know which thing you are about to destroy, and it is the only one of the three that catches the right gesture aimed at the wrong object. Sliding charges motor precision and continuity, which makes it the most natural of the three under a thumb and the least forgiving for a shaky hand or a trackpad. As a rule of thumb: type for the irreversible and named, hold for the physical and quick, slide for touch and for anything that must not happen in a pocket.

That last cost is not a matter of taste, it is a conformance failure waiting to happen. WCAG 2.2 added success criterion 2.5.7, Dragging Movements, which requires that any function operated by dragging also be achievable with a single pointer without dragging. A slide to confirm that is the only way through fails it, and the fix is small: ship a plain button beside the track, or make a tap on the far end of the track commit as well. That is a dragging alternative, and the specimen on this page carries one for exactly this reason. Anything teaching this pattern without it is teaching a bug.

The craft is in the threshold and the release. The track has to be long enough that the gesture reads as deliberate and short enough to finish in one motion without repositioning the hand, which in practice means something like a thumb’s travel rather than the width of the screen. A release before the threshold springs the thumb back, and that spring is the most important animation in the control: it is the interface saying that nothing happened, which is the only way a reader learns that letting go early is safe. Once it commits, do not spring back and do not re-arm, because a guard that resets itself into a live state is a guard that can be tripped twice.