// Default Params
function sum(x = 10, y = 20) {
  return x + y
}

console.log(sum()) // 30

// Rest Params
function sum(x, y, ...abc) { // ...abc = [30,40,50]
  let total = abc.reduce((a,b) => a + b) // 30+40+50 = 120
  return x + y + total // 10 + 20 + 120 = 150
}

console.log(sum(10, 20, 30, 40, 50)) // 150

// Spread Operator
let people = ['foo', 'bar', 'jar']
let others = ['pippo', 'pluto', ...people]
let numbers = [1,2,3,4,5]

console.log(sum(...numbers)) // 15