discourse/app/assets/javascripts/admin/controllers/modals/admin-uploaded-image-list.js

import Controller from "@ember/controller";
import { on, observes } from "discourse-common/utils/decorators";
import ModalFunctionality from "discourse/mixins/modal-functionality";

export default Controller.extend(ModalFunctionality, {
  @on("init")
  @observes("model.value")
  _setup() {
    const value = this.get("model.value");
    this.set("images", value && value.length ? value.split("\n") : []);
  },

  actions: {
    uploadDone({ url }) {
      this.images.addObject(url);
    },

    remove(url) {
      this.images.removeObject(url);
    },

    close() {
      this.save(this.images.join("\n"));
      this.send("closeModal");
    }
  }
});