...運算符可用于淺拷貝

• 深拷貝

let obj1={name:'Jacl'}
let obj2=obj1
obj1["age"]=12
obj2//{name: "Jacl", age: 12}

用Object.assign(obj)實現(xiàn)深拷貝

let obj1={name:'Jacl'}
let obj2=Object.assign( obj1)
obj1["age"]=12
obj2//{name: "Jacl", age: 12}

• 淺拷貝

let obj1={name:'Jacl'}
let obj2={...obj1}
obj1["age"]=12
obj2//{name: "Jacl"}

當(dāng)然，我們也可以在淺拷貝的同時修改所獲對象的屬性

let obj1={name:'Jacl'}
let obj2={...obj1,name:'Zha'}
obj1["age"]=12
obj2//{name: "Zha"}

用Object.assign({}, obj)實現(xiàn)淺拷貝

let obj1={name:'Jacl'}
let obj2=Object.assign({}, obj1)
obj1["age"]=12
obj2//{name: "Jacl"}

數(shù)組同理

[...arr1]

• 那么如果想對[{},{},{}...]形式的數(shù)據(jù)對象進行淺拷貝呢?

一層淺拷貝(不符合要求)

二層淺拷貝(符合要求)

...運算符也有其它用處

• 類型轉(zhuǎn)換
  set轉(zhuǎn)arr(數(shù)組去重)

let s1=new Set([2,1,3,4,3,1])
let arr=[...s1]
arr //[2, 1, 3, 4]

• 獲取對象屬性/方法

let obj={name:'Li',age:2}
let {name}={...obj}
name//"Li"

• 擴充對象屬性(增加數(shù)組元素)

let a=[1,2,3]
let b=[4,...a]
b//[4, 1, 2, 3]

let x={name:'Li'};
let y={age:3,...x};
y//{age: 3, name: "Li"}