扩展运算符详解以及例子

扩展运算符（spread operator）是ES6新增的运算符，用于将一个数组或对象展开成多个独立的元素。以下是扩展运算符的几个例子代码：

1. 数组展开

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const combinedArr = [...arr1, ...arr2];
console.log(combinedArr); // [1, 2, 3, 4, 5, 6]

1. 将数组复制到另一个变量

const arr1 = [1, 2, 3];
const arr2 = [...arr1];
console.log(arr2); // [1, 2, 3]

1. 将字符串转为字符数组

const str = "hello";
const arr = [...str];
console.log(arr); // ['h', 'e', 'l', 'l', 'o']

1. 将伪数组转为数组

function sum(...args) {
  return args.reduce((total, num) => total + num);
}
const nums = { 0: 1, 1: 2, 2: 3, length: 3 };
const result = sum(...Array.from(nums));
console.log(result); // 6

1. 将对象属性复制到另一个对象

const obj1 = { x: 1, y: 2 };
const obj2 = { ...obj1, z: 3 };
console.log(obj2); // {x: 1, y: 2, z: 3}