Interfaces for OOP classes in TypeScript

Interfaces in TypeScript are also widely used as templates for classes. To apply the desired interface to a class, the keyword implements is written after the class name and then the interface name.

Interfaces describe only public properties and methods of a class. The private part is defined in the class itself and is not described in the interface.

Let's try it in practice. Let's say we have the following interface that defines a property and a method:

typescriptinterface IUser {
  name: string;
  greet(): string;
}

Let's make a class that implements this interface. In this class, we should implement the property name and the method greet:

typescriptclass User implements IUser {
  name: string;
  
  constructor(name: string) {
    this.name = name;
  }
  
  greet() {
    return `hello, ${this.name}!`;
  }
}