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();
[a,b,c];  //[1,2,3]
//返回一个对象
function example(){
  return {
    foo:1,
    bar:2
  };
}
let {foo,bar} = example();
foo;  //1
bar;  //2

//参数是一组有次序的值
function f([x,y,z]){
  console.log(x,y,z);
}
f([1,2,3]); //1,2,3
//参数是一组无次序的值
function func({x,y,z}){
  console.log(x,y,z);
}
func({z:3,y:2,x:1}); //1,2,3

let jsonData = {
  id:42,
  status:"OK",
  data:[123,456]       
} ;
let {id,status,data:number} = jsonData;
console.log(id,status,number);  //42 "OK" (2) [123, 456]

var map = new Map();
map.set('first','hello');
map.set('second','world');

for(let [key,value] of map){
  console.log(key,value);
}

//first hello
//second world

//获取键名
for(let [key] of map){
  console.log(key);
}

//first
//second
//获取键值
for(let [,value] of map){
  console.log(value);
}
//hello
//world

const {a,b} = require('source-map');