ES6解构赋值和展开运算符

解构赋值

let ary = [1, 2, 3]
//解构赋值：按照一个数据值的结构，快速解析获取到其中的内容：
//1、项目中一般都是针对与数组或者对象进行解构赋值
//==================数组解构赋值
let [a] = ary;
console.log(a);//1

let [, , c] = ary;
console.log(c);//3

let [a, ...b] = ary;
console.log(a, b);//1 [2, 3]

//如果没有对应值，可以设置默认值
let [a, b, c,d = 0] = ary;
//=================对象解构赋值
let obj = {name: 'xxx', age: 25};
let {name, age} = obj;
console.log(name, age);

let {age} = obj;
console.log(sex);//=>0

let {age: ageAA} = obj;
console.log(ageAA);

…的作用

1.剩余运算符

let array = [12, 23, 45];
let [...arg] = array; =>ary.slice(0);
function fn(context, ...arg) {
	console.log(context, arg); //=>arg是一个数组
}
let obj = {};
fn(obj, 10, 20, 30);

2.展开运算符

console.log(1, ...[2, 3, 4], 5);
// 1 2 3 4 5