confirmation-modal-controller.js

import { Controller } from "stimulus";

export default class extends Controller {
  connect() {
    this.element[this.identifier + "-controller"] = this;
  }

  confirm() {
    return new Promise((resolve, reject) => {
      this.confirmationResolve = resolve;
      this.confirmationReject = reject;

      $(this.element).modal({ backdrop: "static", keyboard: false });
    });
  }

  accept(event) {
    event.preventDefault();
    $(this.element).modal("hide");
    if (this.confirmationResolve) {
      this.confirmationResolve();
    }
  }

  reject(event) {
    event.preventDefault();
    $(this.element).modal("hide");
    if (this.confirmationReject) {
      this.confirmationReject();
    }
  }
}

usage.js

// open the modal and tell it what to do after confirm
this.confirmationModalController.confirm().then(() => {
  this.doWhateverNeededConfirmation()
})