Abstract classes in Typescript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an abstract class named Animal.

Typescript

abstract class [1] {
  abstract makeSound(): void;
}

Drag options to blanks, or click blank then click option'

AAnimal

BDog

CSound

DAnimalSound

Attempts:

3 left

💡 Hint

Common Mistakes

Using a concrete class name like 'Dog' instead of the abstract class name.

Forgetting to use the 'abstract' keyword before the class.

The keyword abstract is used to declare an abstract class. Here, the class name should be Animal.

2fill in blank

medium

Complete the code to correctly extend the abstract class Animal.

Typescript

class Dog extends [1] {
  makeSound(): void {
    console.log('Woof!');
  }
}

Drag options to blanks, or click blank then click option'

AAnimal

BSound

CDogSound

DCreature

Attempts:

3 left

💡 Hint

Common Mistakes

Extending a class that does not exist.

Using a different class name than the abstract class.

The class Dog extends the abstract class Animal to provide an implementation for the abstract method.

3fill in blank

hard

Fix the error in the code by completing the blank with the correct keyword to prevent instantiation of the class.

Typescript

[1] class Animal {
  makeSound(): void {
    console.log('Some sound');
  }
}

const animal = new Animal();

Drag options to blanks, or click blank then click option'

Astatic

Bfinal

Cprivate

Dabstract

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'final' which is not a TypeScript keyword.

Using 'static' or 'private' which do not prevent instantiation.

Marking the class as abstract prevents it from being instantiated directly.

4fill in blank

hard

Fill both blanks to declare an abstract method move in the abstract class Vehicle.

Typescript

abstract class Vehicle {
  [1] [2](): void;
}

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Aabstract

Bmove

Crun

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method name other than 'move'.

Not marking the method as abstract.

The method is declared as abstract and named move without a body in the abstract class.

5fill in blank

hard

Fill all three blanks to implement the abstract method move in the subclass Car.

Typescript

class Car extends Vehicle {
  [1] [2](): void {
    console.log('[3] fast');
  }
}

Drag options to blanks, or click blank then click option'

Amove

Boverride

Cdrives

Attempts:

3 left

💡 Hint

Common Mistakes

Not using the 'override' keyword.

Using a different method name than 'move'.

Logging a wrong string.

The subclass Car uses the override keyword to implement the abstract method move and logs 'drives fast'.