typescript define new property for interface code example

Example 1: typescript class interface

interface IPerson {
  name: string
  age: number
  hobby?: string[]
}

class Person implements IPerson {
  name: string
  age: number
  hobby?: string[]

  constructor(name: string, age: number, hobby: string[]) {
    this.name = name
    this.age = age
    this.hobby = hobby
  }
}

const output = new Person('john doe', 23, ['swimming', 'traveling', 'badminton'])
console.log(output)

Example 2: typescript interface

interface Foo {
    bar: string;
    qux: number;
}
// Creates object implementing interface:
const MyFoo = <Foo> {
    bar: "Hello",
    qux: 7
}
// Or:
const MyFoo: Foo = {
    bar: "Hello",
    qux: 7
}