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 只拷贝一层，更深层的拷贝引用地址

实现方式

for...in

 let obj={name:"zs",age:18,person:{name:"ls"}}
        function clone(obj){
            let cloneObj={}
            for(let key in obj){
                cloneObj[key]=obj[key]            
        }
        return cloneObj;
        }
        let obj1=clone(obj)
        obj.name="change"
        obj.person.name="lz"
        console.log(obj.name);//change
        console.log(obj1.name);//zs
        console.log(obj.person.name);//lz
        console.log(obj1.person.name);//lz

Object.assign

Object.assign(newObj,oldObj)

let obj={name:"zs",age:18,person:{name:"ls"}}
let obj2=Object.assign({},obj)
//console.log(obj2.name);//zs
obj.name="change"
console.log(obj.name);//change
console.log(obj2.name);//zs

扩展运算符

 let obj3={...obj}
        console.log(obj3.name);//zs
        obj.name="change"
        console.log(obj.name);//change
        console.log(obj3.name);//zs
        obj.person.name="change"
        console.log(obj.person.name);//change
        console.log(obj3.person.name);//change

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