Destructuring

// Arrays
const [first, last] = ['Nikola', 'Tesla']

// Objects
let {title, author} = {
  title: 'The Silkworm',
  author: 'R. Galbraith'
}

const scores = [22, 33]
const [math = 50, sci = 50, arts = 50] = scores

//Result:
//math === 22, sci === 33, arts === 50


function greet({ name = 'Rauno' } = {}) {
  console.log(`Hi ${name}!`);
}

greet() // Hi Rauno!
greet({ name: 'Larry' }) // Hi Larry!

function greet({ name, greeting }) {
  console.log(`${greeting}, ${name}!`)
}

greet({ name: 'Larry', greeting: 'Ahoy' })

function printCoordinates({ left: x, top: y }) {
  console.log(`x: ${x}, y: ${y}`)
}
printCoordinates({ left: 25, top: 90 })

or (let {title, artist} of songs) {
  ···
}

const { id, ...detail } = song;

// with object extensions
const options = {
  ...defaults,
  visible: true
}

// No object extension
const options = Object.assign(
  {}, defaults,
  { visible: true })

// with array extension
const users = [
  ...admins,
  ...editors,
  'rstacruz'
]
// No array expansion
const users = admins
  .concat(editors)
  .concat([ 'rstacruz' ])

const fatherJS = { age: 57, name: "Zhang San" }
Object.values(fatherJS)
//[57, "Zhang San"]
Object.entries(fatherJS)
//[["age", 57], ["name", "Zhang San"]]