ES6 解构赋值的用法笔记

1、概念：解构赋值可以理解为对赋值运算符的一种扩展。它主要针对数组或者

对象进行模式匹配，然后对模式中的变量进行赋值。

2、特性：采用ES6解构赋值的方式可以代码的可读性更高、代码书写更加简洁、清晰。

3、解构模型：分为解构源、解构的目标：解构源=解构的目标

4、解构类型：分为数组类型、对象类型。

let [a,b,c]=[5,15,25];
alert(b);//15

let [a,[b,c],d]=[5,[15,25],50];
alert(c);//25

let [a,,b]=[5,15,25];
alert(b);//25

let [a=5,b]=[10,20];
alert(b);//20

let [a,...b]=[10,20,30,40,50];
alert(b);//20,30,40,50

let [a,b,c]="how";
alert(a);//h
alert(b);//o
alert(c);//w

let {name,age}={name="小明",age=25};
alert(name);

let person = {p: ['小明', {age: 25}] };
let {p: [name, { age }] } = person;
alert(name);//小明
alert(age);//25
let person = {p: ['小王', {age: 25}] };
let {p: [name, {  }] } = person;
alert(name);//小王

let person = {p: [{age: 30}] };
let {p: [{ age }, name ] } = person;
alert(name);//undefined
alert(age);//30

let {a,...rest} = {a: 10, b: 20, c: 30, d: 40};
console.log(a);//10
console.log(rest);// Object { b: 20, c: 30, d: 40 }

let {a = 10, b = 5} = {a: 3};
console.log(a);//3
console.log(b);//b
let {a: aa = 10, b: bb = 50} = {a: 10};
console.log(aa);//10
console.log(bb);//50