index.ts

import { DataAccessLayer } from "./DataAccessLayer";
import { Service } from "./Service";

const service = new Service(new DataAccessLayer());

const id1 = service.register({ firstName: "Chris", lastName: "Bauer" });
const id2 = service.register({ firstName: "John", lastName: "Tomson" });
const id3 = service.register({ firstName: "Tom", lastName: "Johnson" });

console.log(service.getUserInfo(id1));
console.log(service.getUserInfo(id2));
console.log(service.getUserInfo(id3));