浅拷贝和深拷贝的理解

心已赠人 2022-11-12 09:37 186阅读 0赞

**1.浅拷贝值的变化相互影响**

let obj1 = {
         a: 1, b: [1, 2, 3], c: '小三', d: new Date(), e: /^0\d{2,3}-?\d{7,8}$/ }
        let obj2 = {
        }
        obj2 = obj1 //浅拷贝
        obj2.a = 5
        console.log(obj2, obj1);

![在这里插入图片描述][2021032315362491.png]  
**2.深拷贝值的变化不受影响**

let obj1 = {
         a: 1, b: [1, 2, 3], c: '小三', d: new Date(), e: /^0\d{2,3}-?\d{7,8}$/ }
        let obj2 = {
        }
        obj2 = JSON.parse(JSON.stringify(obj1)) //深拷贝  
        obj2.a = 5
        console.log(obj2, obj1);

`Tip: 这个写法的弊端：如果对象里有正则编译为空,如果有时间编译出日期格式会变化`  
`"2021-03-23T06:36:41.188Z"<===Tue Mar 23 2021 14:36:41 GMT+0800 (中国标准时间) {}`  
![在这里插入图片描述][20210323153529175.png]  
**3.递归深拷贝(解决上面两个弊端)**

let obj1 = {
         a: 1, b: [1, 2, 3], c: '小三', d: new Date(), e: /^0\d{2,3}-?\d{7,8}$/ }
    
        function deepClone(obj) {
        
            //过滤特殊情况
            if (obj === null) return null
            if (typeof obj !== 'object') return obj
            if (obj instanceof RegExp) {
        
                return new RegExp(obj)
            }
            if (obj instanceof Date) {
        
                return new Date(obj)
            }
            //不直接创建空对象目的：克隆的结果和之前保持相同的所属类
            let newObj = new obj.constructor;
            for (let key in obj) {
        
                if (obj.hasOwnProperty(key)) {
        
                    newObj[key] = deepClone(obj[key])//递归深拷贝
                }
            }
            return newObj
        }
        let obj2 = deepClone(obj1)
        obj2.a = 5
        console.log(obj2, obj1)

![在这里插入图片描述][20210323153229466.png]

[2021032315362491.png]: /images/20221022/6f1d74b6573d44b69ef73e36cc1b56f6.png
[20210323153529175.png]: /images/20221022/a85c2b6903f745c58a9b1b998af31266.png
[20210323153229466.png]: /images/20221022/ee1fbd2596a14c118bacdeb68a67dd5f.png