解构、rest

解构

数组：

const [a, b, c, d = 4] = [1, 2, 3]
console.log(a, b, c, d) // 1 2 3 4

const [a, b, [c, d]] = [1, 2, [3, 4]]
console.log(a, b, c, d) // 1 2 3 4

对象：

const user = {
  name: 'zhangsan',
  age: 10
}
let { age: uage, name: uname } = user // 别名
let { age, name } = user

字符串：

let [a, b, c, d] = 'love'
console.log(a, b, c, d) // l o v e

参数：

function foo([a, b, c]) {
  console.log(a, b, c) // 1 2 3
}
foo([1, 2, 3])

function foo2({ name, age = 18 }) {
  console.log(name, age) // zs 18
}
foo2({
  name: 'zs'
})

---

rest

解构

function foo(a, b, c) {
  console.log(a, b, c) // 1 2 3
}
const arr = [1, 2, 3]
foo(...arr)

const str = 'zs'
const arr = [...str] // [ 'z', 's' ]

合并

const obj = { ...obj1, ...obj2 }
const arr = [...arr1, ...arr2]

arr1.push(...arr2) 

剩余参数

function foo(x, ...args) {
  console.log(x) // 1
  console.log(args) // [ 2, 3, 4 ]
}
foo(1, 2, 3, 4)

const obj4 = {
  name: 'zhangsan',
  age: 18,
  school: '清华大学',
  id: '001'
}
const { name, age, ...rest } = obj4

深拷贝

const obj1 = {
  name: 'zhangsan',
  age: 34
}
const obj2 = {
  ...obj1
}
obj1.name = 'lisi'
console.log(obj1) // {name: 'lisi', age: 34}
console.log(obj2) // {name: 'zhangsan', age: 34}