关于ES6的对象扩展运算符

对象的扩展运算符(...)，用于取出参数对象中的所有可遍历属性，然后拷贝到当前对象之中

对象扩展运算符：

1. 复制对象

let obj1 = { x: 1, y: 2, z: 3 }

let obj2 = { ...obj1 }

obj2 = { x: 1, y: 2, z: 3 }

2. 合并对象

let obj1 = { x: 1, y: 2, z: 3 }

let obj2 = { x: 4, y: 5, z: 6 }

let obj3 = { ...obj1, ...obj2 }

obj3 = { x: 1, y: 2, z: 3, x: 4, y: 5, z: 6 }

3. 自定义属性

let obj1 = { x: 1, y: 2, z: 3 }

let obj2 = { ...obj1, a: 4, b: 5, c: 6 }

obj2 = { x: 1, y: 2, z: 3, a: 4, b: 5, c: 6 }

注意：若自定义属性在扩展运算符的后面，且与扩展运算符内的属性同名，则扩展运算符内的属性会被覆盖掉

数组扩展运算符

1. 复制数组

let arr1 = [1, 2, 3]

let arr2 = [ ...arr1 ]

arr2 = [1, 2, 3]

2. 合并数组

let arr1 = [1, 2, 3]

let arr2 = [4, 5, 6]

let arr3 = [ ...arr1, ...arr2 ]

arr3 = [1, 2, 3, 4, 5, 6]

3. 字符串变数组

let arr1 = [1, 2, 3]

let str1 = 'hello'

let arr2 = [...arr1, ...str1]

arr2 = [ 1, 2, 3, "h", "e", "l", "l", "o" ]