Using Interfaces with Classes in TypeScript

Interfaces defines the structure of an object. Here is a structure of a Car object using interface.

interface Car {
  model: string;
  year: number;

  show(message: string): void;
}

Later we can create a class that implements the Car interface.

class BMW implements Car {
  model: string;
  year: number;

  constructor(m: string, y: number) {
    this.model = m;
    this.year = y;
  }

  show(message: string) {
    console.log(message);
  }
}

The keyword rightly tells implements because it is mandatory to implement all properties and methods listed in the interface.

It is ok to add more properties and methods to the class.