How to override quick_list_widget.js file using custom app

Hello,
I am trying to override the quick_list_widget.js file, the class is defined like this "export default class QuickListWidget extends Widget ". when i am try to import QuickListWidget class in custom app i am getting import error (Uncaught SyntaxError: Cannot use import statement outside a module)

How to override this class?

Please check the reference: