Inheritance in TypeScript

class Puppy extends Dog {
    whine() { console.log("whimper"); }
}

Full lesson:

Inheritance is one of the four classic OOP pillars (along with encapsulation, polymorphism, and abstraction). The idea is simple: most real-world things are kinds of other things — a Puppy is a Dog, a Car is a Vehicle, a Manager is an Employee. When you model that "is-a" relationship in code, the child class gets the parent's data and behavior automatically.

What gets inherited?

• Fields — the Puppy has a name field even though we only declared it on Dog.
• Methods — the Puppy can call bark() even though we only defined it on Dog.
• The contract — anywhere code expects a Dog, you can pass a Puppy (we'll see this when we cover polymorphism).

What you still write

• A constructor only if you need one. If the child declares its own, it must call super(...) to forward arguments to the parent's constructor (the parent's fields need initializing). If it declares none, as here, the parent's constructor is used and new Puppy("Buddy") passes the name straight to it.
• Any new methods or new fields specific to the child.

Your task

Below the Dog class, create a Puppy class that inherits from Dog and adds one new method, whine(), that prints "whimper". The harness creates a Puppy named "Buddy", calls its inherited bark(), and then its new whine().

Expected output:

Woof! I am Buddy
whimper