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:

interface 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:

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

Create an interface IMath with properties num1 and num2 and a method getDiv that will divide the first number by the second.

Make a class Math that implements the interface IMath.