Interfaces

An interface is a code contract that defines a particular schema. Any artifacts like classes and functions implementing an interface should comply with this schema. Interfaces are beneficial when we want to enforce strict typing on classes generated by factories or when we define function signatures to ensure that a particular typed property is found in the payload.

Interfaces disappear during transpilation and are not included in the final JavaScript code.

In the following snippet, we define an interface for managing products:

interface Product {
  name: string;
  price: number;
  getCategories: () => string[];
}

An interface can contain properties and methods. In the preceding snippet, the Product interface contains name and price properties. It also defines the getCategories method. A class can use an interface by adding the implements keyword and the interface name in the class declaration:

class Keyboard implements Product {
  name: string = 'Keyboard&apos...