拷贝

拷贝

拷贝： 复制对象

浅拷贝： 只复制一层对象

深拷贝： 复制得到不一样的对象

实现拷贝

浅拷贝

let obj = {
name: 'jack',
age: 18,
fun: {
        swiming: '游泳',
},
}
//  {...obj}  [...arr]
// let newObj = { ...obj } // 浅拷贝,如果属性值是对象不能拷贝
// let newObj = Object.assign(obj) 
  newObj.name = 'rose'
  newObj.fun.swiming = '打游戏'
  console.log('newObj :',newObj.name,  '  oldObj :',obj.name);
  console.log('newObj fun :',newObj.fun.swiming,  '  oldObj  fun :',obj.fun.swiming);
  console.dir(newObj);
  console.dir(obj);

深拷贝

JSON对象：1.JSON.stringify(obj) //obj --> 字符串

注意：只能是Object形式对象

2.JSON.parse(str) //字符串 --> obj

注意：字符串必须是JSON格式

function test1() {
        let objStr = JSON.stringify(obj)
        console.log(obj)
        console.log(objStr, typeof objStr)

        let str = '{"num":1001,"score":98}'
        let obj1 = JSON.parse(str)
        console.log(obj1)
        console.log(obj1.num)
}

        let obj = {
	name: 'jack',
	age: 18,
	fun: {
                swiming: '游泳',
                },
            say:function(){
                console.log('说话');
            },
            score:undefined
        }
        // 利用JSON实现深拷贝
        // let str = JSON.stringify(obj)  //obj->str
        // let newObj = JSON.parse(str)  // str->obj
        let newObj = JSON.parse(JSON.stringify(obj))
        newObj.name = 'rose'
        newObj.age = 20
        newObj.fun.swiming = '玩游戏'

        console.dir(newObj)
        console.dir(obj)

递归实现深拷贝

  function cloneObj(obj){
       let newObj = Array.isArray(obj)? []:{} // 存储拷贝的原对象属性方法
       for(const key in obj){
           if(obj[key] && typeof obj[key] === 'object'){
               newObj[key] = cloneObj(obj[key])
           }else{
               newObj[key] = obj[key]
             }
          }
            return newObj
        }
let obj = {
	name: 'jack',
	age: 18,
	fun: {
                swiming: '游泳',
                },
                say: function () {
                console.log('说话')
                },
                score: undefined,
		}
        let newObj = cloneObj(obj)

        newObj.name = 'rose'
        newObj.age = 20
        newObj.score = 98
        newObj.fun.swiming = '玩游戏'

        console.dir(newObj)
        console.dir(obj)