If an event is cancelable, the preventDefault method is used to signify that the event is to be canceled, meaning any default action normally taken by the implementation as a result of the event will not occur.
The stopPropagation method is used prevent further propagation of an event during event flow. The event will complete dispatch to all listeners on the current EventTarget before event flow stops. This method may be used during any stage of event flow.
Events of that type are usually implemented in custom components.