Show an example of ES6 classes to create objects and inherit properties?

Q: Show an example of ES6 classes to create objects and inherit properties?

class Animal { constructor(name) { this.name = name; this.isAlive = true; } // This method lives on Animal.prototype eat() { console.log(`${this.name} is eating.`); } } class Dog extends Animal { constructor(name, breed) { // 1. Call the parent constructor first! super(name); // 2. Then add child-specific properties this.breed = breed; } // Overriding a method (Polymorphism) eat() { super.eat(); // Call the parent version console.log(`${this.name} prefers steak.`); } bark() { console.log("Woof! Woof!"); } } const myDog = new Dog("Rex", "German Shepherd");

Difficulty: 5/10

class syntax, inheritance, constructor

javascript

Scenario Questions

0-2 years experience

1We need a simple User class with name and email, and an Admin subclass that adds a role property. How would you implement this using ES6 classes?
2If you create an instance of Admin and call a method defined only on User, what will be logged? Show the code and explain the result.
3What error do you get if you omit super() in the Admin constructor, and why?

Follow-up Questions

What happens if the subclass constructor doesn't call super()?
How would you test that the inheritance works as expected?
Can you think of any edge cases when extending built‑in objects?