/**
  * Class representing an originator (instance where content will be saved).
  * @class
  */
class Originator {
  /**
     * Create an originator.
     */
  constructor(content) {
     this._content = content;
  }
  /**
     * Get the originator content.
     * @return {array} The originator content value.
     */
  get content() {
    return this._content;
  }
}

/**
  * Class representing a caretaker (instance where content will be saved).
  * @class
  */
class CareTaker {
  /**
   * Create an careTaker.
   */
  constructor() {
    this._content = [];
  }

  /**
     * Set the originator content.
     * @param {any} value - some new value to add
     * @return {array} updated caretaker content value.
     */
  setValue(value) {
    this._content.push(value);
    return this._content;
  }

  /**
    * Get current caretaker content
    * @return {array} current caretaker content
    */
  getValues() {
    return this._content;
  }

  /**
    * Return new instance of originator with current content
    * @return {Originator} originator instance
    */
  save() {
    return new Originator(this._content);
  }

  /**
    * Restore caretaker content from originator instance
    * @param {Originator} - originator instance
    */
  restore(originator) {
    this._content = originator.content;
  }
}

// ============================================================================
// USAGE
// ============================================================================

const caretaker = new CareTaker();

caretaker.setValue('First value');
caretaker.setValue('Second value');
caretaker.setValue('Third value');
console.log(caretaker.getValues())
// ['First value', 'Second value', 'Third value']

const originator = caretaker.save();
console.log(originator.content)
// ['First value', 'Second value', 'Third value']

caretaker.setValue('Some another value');
console.log(caretaker.getValues())
// ['First value', 'Second value', 'Third value', 'Some another value']

caretaker.restore(originator);
console.log(caretaker.getValues());
// ['First value', 'Second value', 'Third value']