ES6 允许按照一定模式，从数组和对象中提取值，对变量进行赋值，这被称为解构。

let [a, b] = [1, 2] // a = 1, b = 2
let [a, b, c = 100] = [1, 2]

let {hello, world} = {hello: 1, world: 2}
let {hello = 1, world} = {world: 2}
let {hello:w, world} = {world: 2}