Test JavaScript object access performance (in TypeScript)

test.ts

interface Named {
  firstName: string;
  lastName: string;
}

class Person implements Named {
  firstName: string;
  lastName: string;

  constructor(firstName: string = '', lastName: string = '') {
    this.firstName = firstName;
    this.lastName = lastName;
  }

  get fullName(): string {
    return this.firstName + ' ' + this.lastName;
  }
}

function fullName(named: Named) {
  return named.firstName + ' ' + named.lastName;
}

it('', () => {
  const staticData: Named = {firstName: 'Anton', lastName: 'K'};
  const copiedData: Named = {...staticData};
  const extendedData = {firstName: 'Anton', lastName: 'K'} as any;
  extendedData.xxx = 'something else';
  const modifiedData: Named = {firstName: 'Anton', lastName: 'K'};
  modifiedData.firstName = 'John';
  const json = JSON.parse(JSON.stringify(staticData));

  const person = new Person('Anton', 'K');
  const person1: Person = Object.assign(new Person(), staticData);
  const person2: Person = Object.setPrototypeOf(staticData, new Person());
  const person3: Person = Object.setPrototypeOf(staticData, Person.prototype);

  measureTime(() => fullName(staticData));
  measureTime(() => fullName(copiedData));
  measureTime(() => fullName(extendedData));
  measureTime(() => fullName(modifiedData));
  measureTime(() => fullName(json));
  measureTime(() => fullName(person));
  measureTime(() => person.fullName);
  measureTime(() => person1.fullName);
  measureTime(() => person2.fullName);
  measureTime(() => person3.fullName);
});

function measureTime(f: () => void) {
  const start = Date.now();
  for (let i = 0; i < 100000000; i++) {
    f();
  }
  console.log(f.toString(), f(), Date.now() - start);
}