For Medium Article: https://medium.com/swlh/protect-your-javascript-applications-from-api-data-401a73c7c80b

baseModelTypeScript.ts

import LocationModel from './LocationModel';
import CarModel from './CarModel';

import {BaseModel} from 'sjs-base-model';

class PersonModel extends BaseModel {
  public readonly firstName: string = '';
  public readonly lastName: string = '';
  public readonly age: string = 0;
  public readonly address: LocationModel = LocationModel as any;
  public readonly cars: CarModel[] = [CarModel as any];

  /*
   * Client-Side properties (Not from API)
   */
  public fullName: string = '';

  constructor(data: Partial<PersonModel>) {
    super();

    this.update(data);
  }

  public update(data: Partial<PersonModel>): void {
    super.update(data);

    this.fullName = `${this.firstName} ${this.lastName}`;
  }
}