let [a, b, c] = [1, 2, 3];

let [foo, [[bar], baz]] = [1, [[2], 3]];

foo //

bar //

baz //

let [ , , third] = ["foo", "bar", "baz"];

third // "baz"

let [x, , y] = [1, 2, 3];

x //

y //

let [head, ...tail] = [1, 2, 3, 4];

head //

tail // [2, 3, 4]

let [x, y, ...z] = ['a'];

x // "a"

y // undefined

z // []

let [foo = true] = [];

foo // true

let [x, y = 'b'] = ['a']; // x='a', y='b'

let [x, y = 'b'] = ['a', undefined]; // x='a', y='b'

let [x = 1] = [null];

x // null

let [x = 1, y = x] = [2];    // x=2; y=2

let { bar, foo } = { foo: "aaa", bar: "bbb" };

foo // "aaa"

bar // "bbb"

var { foo: baz } = { foo: 'aaa', bar: 'bbb' };

baz // "aaa"

let obj = {};

let arr = [];

({ foo: obj.prop, bar: arr[0] } = { foo: 123, bar: true });

obj // {prop:123}

arr // [true]

let x = 1;

let y = 2;

[x, y] = [y, x];

// 返回一个数组

function example() {

  return [1, 2, 3];

}

let [a, b, c] = example();

// 返回一个对象

function example() {

  return {

    foo: 1,

    bar: 2

  };

}

let { foo, bar } = example();

// 参数是一组有次序的值

function f([x, y, z]) { ... }

f([1, 2, 3]);

// 参数是一组无次序的值

function f({x, y, z}) { ... }

f({z: 3, y: 2, x: 1});

let jsonData = {

  id: 42,

  status: "OK",

  data: [867, 5309]

};

let { id, status, data: number } = jsonData;

console.log(id, status, number);

// 42, "OK", [867, 5309]

jQuery.ajax = function (url, {

  async = true,

  beforeSend = function () {},

  cache = true,

  complete = function () {},

  crossDomain = false,

  global = true,

  // ... more config

}) {

  // ... do stuff

};

var map = new Map();

map.set('first', 'hello');

map.set('second', 'world');

for (let [key, value] of map) {

  console.log(key + " is " + value);

}

// first is hello

// second is world