We can use an indexed access type to look up a specific property on another type. Let’s take a look at the example:

type User = {
  id: number;
  username: string;
  email: string;
  address: {
    city: string;
    state: string;
    country: string;
    postalCode: number;
  };
  addons: { name: string, id: number }[];
};

type id = User["id"]; // number
type Session = User["address"]; 
// {
//   city: string;
//   state: string;
//   country: string;
//   postalCode: string;
// }
type Street = User["address"]["state"]; // string
type Addons = User["addons"][number]; // { name: string; id: number; }

Here we create a new type such as id, Session, Street, Addons from the existing object.

or we can use it directly in a function like this:

function printAddress(address: User["address"]): void {
  console.log(`
    city: ${address.city},
    state: ${address.state},
    country: ${address.country},
    postalCode: ${address.postalCode}
  `);
}