parent.addEventListener('click', e => {
const wasHandled = e.defaultPrevented;
if (wasHandled) return;
// Handle event
});
e.defaultPrevented is a boolean that indicates whether preventDefault() was called on the event by any previous handlers. This is useful for cooperative event handling where multiple handlers might process the same event - checking defaultPrevented allows handlers to respect decisions made by other handlers that executed earlier in the propagation path. This pattern is commonly used in complex applications where different components might need to handle or prevent the same event.