ES6 变量解构赋值详解：数组与对象模式匹配

var [a,b,c] = [1,2,3];
a // 1;
b // 2;
c // 3;

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

let [,,third] = ['foo','bar','baz'];
third //'baz'

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

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

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

function* fibs(){
 var a = 0;
 var b = 1;
 while(true){
  yield a;
  [a,b] = [b,a+b];
 }
}

var [first,second,third,fourth,fifth,sixth] = fibs();
sixth // 5

var [foo=true] = [];
foo //true

var [x = 1] = [undefined]
x // 1

var [x = 1] = [null]
x // null

function f(){
 console.log('aaa')
}

let [x = f()] = [1]

 var {foo,bar} = {foo:'aaa',bar:'bbb'}
 foo // 'aaa'
 bar // 'bbb'

var {bar,foo} = {foo:'aaa',bar:'bbb'}
foo //'aaa'
bar //'bbb'


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

var {foo:baz} = {foo:'aaa'}
baz //'aaa'

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

var obj = {
 p: [
  'hello' ,
  {
   y : 'world'
  }
 ]
}

var {p:[x,{y}]} = obj

x //'hello'
y //'world'

var {x=3} = {x:undefined}
x //3

var {x=3} = {x:null}
x //null

var {foo:{bar}} = {baz:'baz'}