扩展运算符 (...) 用法demo

一、...

let obj1 = {top:100,left:200};

let obj2 = {height:500,width:200};

let obj3 = {

...obj1,

...obj2,

}

console.log(obj3)  //{top: 100, left: 200, height: 500, width: 200}

2.数组  [1,2,3,4]    =>    1,2,3,4

let arr1 = [1,2,3,4,5];

console.log(...arr1);//1,2,3,4,5

console.log(Math.max(...arr1))   等同于  Math.max(1,2,3,4,5)