Inheritance and Interfaces in TypeScript: Usage and Benefits

Inheritance and interfaces are two important concepts in TypeScript, and they play an important role in application development. Here is a discussion of these concepts and their uses and benefits in application development:



Inheritance in TypeScript allows a subclass to inherit properties and methods from a superclass. The subclass can extend and enhance the existing features of the superclass.

To use inheritance, we use the extends keyword to declare that a subclass inherits from a superclass.

For example:

class Animal {
  name: string;

  constructor(name: string) { = name;

  eat() {
    console.log( + " is eating.");

class Dog extends Animal {
  bark() {
    console.log( + " is barking.");

const dog = new Dog("Buddy");; // Output: "Buddy is eating."
dog.bark(); // Output: "Buddy is barking."

In the above example, the Dog class inherits from the Animal class and extends it by adding the bark() method. The Dog class can use the eat() method inherited from the Animal class.



Interfaces in TypeScript define a set of properties and methods that an object must adhere to. They specify a contract for objects that share common features.

To use interfaces, we use the interface keyword to declare an interface.

For example:

interface Shape {
  calculateArea(): number;

class Circle implements Shape {
  radius: number;

  constructor(radius: number) {
    this.radius = radius;

  calculateArea() {
    return Math.PI * this.radius * this.radius;

const circle = new Circle(5);
console.log(circle.calculateArea()); // Output: 78.53981633974483

In the above example, the Shape interface defines a calculateArea() method that every object must adhere to. The Circle class implements the Shape interface and provides an implementation for the calculateArea() method.


Benefits of inheritance and interfaces in application development:

  • Inheritance facilitates code reuse and reduces duplication. When a subclass inherits from a superclass, it can reuse the properties and methods already implemented in the superclass.
  • Interfaces define contracts and enforce adherence to the specified interface, ensuring that objects meet the required criteria. They establish a common structure for development and usage of objects.
  • Both inheritance and interfaces contribute to flexibility in design and application development, enabling concepts such as polymorphism and code reuse.


In summary, inheritance and interfaces are important concepts in TypeScript. They play crucial roles in application development, promoting code reuse, flexibility, and adherence to specified contracts.