/** @odoo-module **/
import { FormController } from "@web/views/form/form_controller";
import {patch} from "@web/core/utils/patch";

patch(FormController.prototype, "CustomFormController", {

	​getActionMenuItems() {
   	​//your code
		​​this._super.apply(this, arguments);
   	​//your code
	​}

});

Hi,

Please refer to the code below. It will give you an idea on how to inherit OWL Js:

/** @odoo-module **/

import { FormController } from "@web/views/form/form_controller";

export class CustomFormController extends FormController {

getActionMenuItems() {

const superVals = super.getActionMenuItems();

// Your code

return superVals;

}

export const CustomFormView = {

...formView,

Controller: CustomFormController,

};

registry.category("views").add("custom_form", CustomFormView);

Hope it helps