浅析深拷贝和浅拷贝的区别_浅拷贝和深拷贝什么时候用

var obj1 = {
        age: 10,
        sex: "男",
        car: ["奔驰", "宝马", "特斯拉", "奥拓"]
      };
      //另一个对象
      var obj2 = {};

      //写一个函数,作用:把一个对象的属性复制到另一个对象中,浅拷贝
      //把a对象中的所有的属性复制到对象b中
      function shallowCopy(obj,targetObj){
        for (let key in obj){
          targetObj[key] = obj[key];
        }
      }
      shallowCopy(obj1, obj2);
      console.dir(obj2);//开始的时候这个对象是空对象
      console.dir(obj1);//有属性
      //change car attribute
      obj1.car.push("奥迪");
      //the car of obj2 change,too.for the point of the car in obj2 is same as the obj1
      console.log(obj2.car);

      // 第二种
      var obj3 = obj1;
      console.dir(obj3);

var obj1 = {
        age: 10,
        sex: "男",
        car: ["奔驰", "宝马", "特斯拉", "奥拓"],
        dog: {
          name: "大黄",
          age: 5,
          color: "黑白色"
        }
      };

      var obj2 = {};//空对象
      //通过函数实现,把对象a中的所有的数据深拷贝到对象b中
      // use recursion
      function deepCopy(obj,targetObj){
        for (let key in obj){
          let item = obj[key];
          if (item instanceof Array){//if array
            targetObj[key] = [];
            deepCopy(item,targetObj[key]);
          }else if (item instanceof Object){//if object
            targetObj[key] = {};
            deepCopy(item,targetObj[key]);
          }else {//normal attribute
            targetObj[key] = obj[key];
          }
        }
      }
      deepCopy(obj1,obj2);
      console.dir(obj1);
      console.dir(obj2);