const person = {
first_name: 'Monica',
last_name: 'Geller',
phone: '915-996-9739',
email: 'monica37@gmail.com',
street: '495 Grove Street',
city: 'New York',
country: 'USA',
};
const keys = Object.keys(person);
console.log(keys);
// ['first_name', 'last_name', 'phone', 'email', 'street', 'city', 'country'];