After reading this event_touchcancel doc:
The touchcancel event occurs when the touch event gets interrupted.
Different devices will interrupt a touch event at different actions, and it is considered good practice to include this event to clean up code if this "error" should occur.
and w3c event-touchcancel. I am still confused.
What does "when the touch event gets interrupted" means? Is there any specific situation that interrupts the touch event? When will touchcancel event be triggered?