function onUp(ev) {
            var event = normalizeEvent(ev);

            if (pointerActive && event.id === pointerId) {
                stopTracking();
            }
        }
function onUp(ev) {
            var event = normalizeEvent(ev);

            if (pointerActive && event.id === pointerId) {
                stopTracking();
            }
        }
function onUp ( ev ) { var event = normalizeEvent ( ev ) ; if ( pointerActive && event . id === pointerId ) { stopTracking ( ) ; } }
Handles up/end events
@param {Object} ev Normalized event
Handles up / end events