Interface Methods in TypeScript

Object interfaces can also add object methods. Let's add a method to our interface that should greet the user. To do this, we must specify the method name, parameter types, and return type:

interface IUser {
	name: string;
	age: number;

	greet(text: string): string;
}

Let's implement our method in an object:

let user: IUser = {
	name: 'john',
	age: 30,

	greet(text: string): string {
		return text + ', ' + this.name
	}
}

Let's call our method:

console.log(user.greet('hello')); // 'hello, john'

For the IUser interface, implement a method to check the age. If the user's age is less than 18, display a message that access is denied.

Create an interface IMath with properties num1 and num2, and a method getSum that will sum both numbers.