Event.cancelable

The cancelable read-only property of the Event interface indicates whether the event can be canceled, and therefore prevented as if the event never happened.

If the event is not cancelable, then its cancelable property will be false and the event listener cannot stop the event from occurring.

Most browser-native events that can be canceled are the ones that result from the user interacting with the page. Canceling the click, wheel, or beforeunload events would prevent the user from clicking on something, scrolling the page with the mouse wheel, or navigating away from the page, respectively.