The correct method is preventDefault(). In an HTML form submission workflow, the browser's default action is to submit the form, which commonly navigates away from the current page or reloads it. Calling event.
preventDefault() inside the form's submit event handler cancels that default action, allowing the current form state to remain visible while custom validation logic displays error messages. MDN defines preventDefault() as the method that cancels the default action normally taken by the implementation for that event. The submit event is the correct event context because it fires when the form submission is triggered. defaultPrevented is only a Boolean property indicating whether cancellation has already occurred; it does not cancel anything.
cancelable only reports whether an event can be canceled. abort is not the correct form-validation event method. References/topics: HTML5 form validation, custom validation messages, submit event handling, event cancellation, preserving user input.