深浅拷贝

1.引用传递是浅拷贝,传递的是地址

　　例如obj2的改变，obj1也会改变

 var obj={
        name:"admin"
    }
    var obj2=obj
    console.log(obj)    //{name: "admin"}
    console.log(obj2)   //{name: "admin"}
　　
    obj2.name="root"
    console.log(obj)    //{name: "root"}
    console.log(obj2)   //{name: "root"}

2深拷贝

　　2.1 深拷贝1:遍历对象读取每个键值对，逐个复制，但是后面会有缺点

    var obj={
            name:"admin"
        }
    var obj2={};
    for(var i in obj){
        obj2[i]=obj[i]
    }
    console.log(obj)    //{name: "root"}
    console.log(obj2)   //{name: "root"}

    obj2.name="root";
    console.log(obj)    //{name: "root"}
    console.log(obj2)   //{name: "root"}

    缺点
    var obj={
        name:{
            name1:"admin"
        }
    }
    var obj2={};
    for(var i in obj){
        obj2[i]=obj[i]
    }
    console.log(obj)    //name: {name: "admin"}
    console.log(obj2)   //name: {name: "admin"}

    obj2.name.name1="root"
    console.log(obj)    //name: {name1: "root"}
    console.log(obj2)   //name: {name1: "root"}
    此时会把obj内的属性值也会改变　　

 

　　2.2 深拷贝2：利用字符的值传递，将对象转成字符再转回来

var obj = {
        name:{
            name1:{
                name2:"admin"
            }
        }
    }
    // JSON.parses是字符转对象，JSON.stringify是对象转字符
    var obj2=JSON.parse(JSON.stringify(obj));
    console.log(obj)    //obj
    console.log(obj2)   //obj
    obj2.name.name1.name2="root";
    console.log(obj)    //name:"root"
    console.log(obj2)   //name:"root"

　　2.3深拷贝3：利用Object.create()实现继承

var obj={
        name:"admin"
        
    }
    var obj2=Object.create(obj);
    console.log(obj)    //{name: "admin"}
    console.log(obj2)   //{}

    obj2.name="root"
    console.log(obj.name)   //admin
    console.log(obj2.name)  //root
    obj2.__proto__.name = "root"
    console.log(obj.name)   //root
    console.log(obj2.name)  //root

// 相当于继承了原型，obj是obj2的父级，修改obj2不会影响obj，除非在obj2上修改原型