Classes

class Course {
  constructor(title, price) {
    this.title = title;
    this.price = price;
  }

  describe() {
    return `${this.title} -- $${this.price}`;
  }
}

class MasteryCourse extends Course {
  describe() {
    return `${super.describe()} (Mastery)`;
  }
}

JS classes are largely syntax sugar over its prototype-based object system, but they read the same as classes in Java or Python, which is why most modern JS is written this way rather than with raw prototypes.