javaScript中深拷貝和淺拷貝

• 深拷貝和淺考都是對複雜對象的操作

var obj = {
     name: "zhangsan"
     age: ["26","30"]
     person:{
        man:"26",
     }
}
           

深拷貝

• 另外在堆記憶體中占用一塊單獨堆記憶體存放資料，内容和原來的對象一樣,更改原來的對象，深拷貝的對象不會改變。
• 實作深拷貝用得比較多的方法是 JSON.parse(JSON.stringify())

var obj = {
				nama: 'zhangsan',
				age: ['25', '26'],
			}
			const obj1 = JSON.parse(JSON.stringify(obj))
			obj1.nama = 'zhaosi'
			obj1.age[1] = '30'
			console.log(obj, obj1)
           

{nama: “zhangsan”, age: Array(2)}age: Array(2)0: "25"1: “26”

{nama: “zhaosi”, age: Array(2)}age: (2) [“25”, “30”]nama: “zhaosi”

淺拷貝

• 隻拷貝對象的引用，（對象的”引用值“也可以是屬性為引用類型）當原對象引用發生改變，拷貝的對象也發生變化。

var shallowCopy = (obj) => {
				const result = {}
				for (let key in obj) {
					if (obj.hasOwnProperty(key)) {
						result[key] = obj[key]
					}
				}
				return result
			}
			const start = {
				name: 'zhangsan',
				age: 25,
				friend: {
					name: 'lisi',
				},
			}
			const foo = shallowCopy(start)
			foo.friend.name = 'zhaosi'
			console.log(start)
           

{name: “zhangsan”, age: 25, friend: {…}}

age: 25

friend:

name: “zhaosi”

proto: Object

name: “zhangsan”