Protected Properties in OOP in JavaScript

Let's also introduce protected properties. Let's also start their names with an underscore. Let's look at an example. Let's make a parent class with a protected property containing age:

javascriptclass User {
  setAge(age) {
    this._age = age;
  }
  getAge() {
    return this._age;
  }
}

In the descendant class we will create a method that increases the age by one:

javascriptclass Student extends User {
  incAge() {
    this._age++;
  }
}

javascriptclass User {
  #name;
  
  setName(name) {
    this.#name = name;
  }
  getName() {
    return this.#name;
  }
}

class Employee extends User {
  setName(name) {
    if (name.length > 0) {
      this.#name = name;
    }
  }
}