NativeScript/apps/app/ui-tests-app/list-view/main-view-model.ts

import { Observable } from "tns-core-modules/data/observable";
import { ObservableArray } from "tns-core-modules/data/observable-array";

export class Item extends Observable {
  private _name: string;
  private _id: number;

  constructor(name: string, id: number) {
    super();
    this._name = name;
    this._id = id;
  }

  get name(): string {
    return this._name;
  }

  set name(value: string) {
    if (this._name !== value) {
      this._name = value;
      this.notifyPropertyChange("name", value)
    }
  }

  get id(): number {
    return this._id;
  }

  set id(value: number) {
    if (this._id !== value) {
      this._id = value;
      this.notifyPropertyChange("id", value)
    }
  }

  public toString() {
    return `${this.name} ${this.id}`;
  }
}

export class ViewModel extends Observable {
  private _items: ObservableArray<Item>;

  get items(): ObservableArray<Item> {
    this._items = new ObservableArray<Item>();
    for (let i = 0; i < 100; i++) {
      this._items.push(new Item(`Item`, i));
    }
    return this._items;
  }
}