'use strict';

const person = {

name: 'Marcus',

city: 'Roma',

born: 121

};

if ('name' in person) {

console.log('Person name is: ' + person.name);

}

for (const key in person) {

const value = person[key];

console.dir({ key, value });

}

// Variables to hash

const name = 'Marcus Aurelius';

const city = 'Rome';

// Old style

const a = {

name,

city

};

// New style

const b = { name, city };

// Dynamic field name

const fieldName = 'city';

const fieldValue = 'Roma';

const person2 = {

name: 'Marcus Aurelius',

[fieldName]: fieldValue

};

// Expression in field name

const person3 = {

name: 'Marcus Aurelius',

['city' + 'Born']: fieldValue

};

// Function in field name

function fn(s) {

return s + 'Born';

}

const person4 = {

name: 'Marcus Aurelius',

[fn('city')]: fieldValue

};