index.ts

interface userType{
  id: number,
  name: string,
  email: string,
  age?:number
}

let user: userType = {
  id: 10,
  name:'Rahul',
  email:'a@g.com',

}
console.log(user.id)
// 10

let user1: userType ={
  id: 11,
  name: 'Rahul',
  email: 'a@g.com'
}
console.log(user1.id)
// 11

let user2: userType ={
  id: 12,
  name: 'R',
  email: 'q@y.com',
  age: 20
}
console.log(user2.id)
// 12