ES6-destructuring

var arr = [1,2];
var one = arr[0];
var two = arr[1];
console.log(one, two)

//인덱스를 기준으로 배열로부터 요소를 추출하여 변수에 할당한다.
const arr = [1, 2];
const [hi, hello] = arr;
console.log(hi, hello); //1, 2
let q, w, e;
[q, w] = [1, 2];
console.log(q, w); // 1, 2
[q, w] = [1]; // 1, undefined
[q, w, e = 5] = [1, 2];
console.log(q, w, e) // 1, 2, 5
[q, ...w] = [1, 2, 3, 4, 5];
console.log(q, w) // 1, [2,3,4,5]
const arr = [1, 2, 3, 4, 5];
const [a, , b] = arr  //1, 3 공백이 처리가 안되었다.

var ob = {first: 'sang', last: 'lee'};
var name = {};
name.first = ob.first;
name.last = ob.last;
console.log(name) // {first: 'sang', last: 'lee'}

const ob = {first: 's', last: 'l'};
const {first, last} = ob;
console.log(first, last); // s, l

const {prop1: item1, prop2: item2} = {prop1: 1, prop2: 2};
console.log({prop1: item1, prop2: item2}); // {prop1: 1, prop2: 2}
function padding() {
  const left = 1, right = 2, top = 3, bottom = 4;
  return {left, right, top, bottom};
}
const {left, bottom} = padding();
console.log(left, bottom); // 1, 4