const person1 = {};
person1['firstname'] = 'Mario';
person1['lastname'] = 'Rossi';
console.log(person1.firstname);
// expected output: "Mario"
const person2 = {
firstname: 'John',
lastname: 'Doe'
};
console.log(person2['lastname']);
// expected output: "Doe"
const person1 = {};person1['firstname'] = 'Mario';person1['lastname'] = 'Rossi';console.log(person1.firstname);// expected output: "Mario"const person2 = { firstname: 'John', lastname: 'Doe'};console.log(person2['lastname']);// expected output: "Doe"