浅拷贝和深拷贝的一些理解

Posted 2020-12-16 xu3241

<script>

        /*

            1,浅拷贝只拷贝一层，更深层次对象级别的只拷贝引用

            2，深拷贝拷贝多层，每一级别的数据都会拷贝 

         */

         var obj = {

             id:1,

             name:‘andy‘,

             msg: {

                 age:18

             },

             color:[‘pink‘,‘red‘]

         }

         //此处为浅拷贝  只能拷贝最外一层 对于深层次的对象只是共享了地址

         var o = {}

        //  for(var k in obj){

        //      //k 属性名，obj[k] 属性值

        //      o[k] = obj[k]

        //  }

        //es6语法浅拷贝

        // Object.assign(o,obj)

        //  console.log(o);

         

         //深拷贝  对于深层次对象重新开辟空间，不是单纯的共享一个对象

            function deepCopy(newobj,oldobj){

                for(var k in oldobj){

                    //判断数据类型为哪种数据类型

                    var item = oldobj[k];

                    //是否为数组   数组最先判断，因为数组也是对象，先写object会覆盖对数组的判断

                    if(item instanceof Array){

                        newobj[k] = []

                        deepCopy(newobj[k],item)

                    //是否为对象

                    }else if(item instanceof Object){

                        newobj[k] = {}

                        deepCopy(newobj[k],item)

                    //简单数据类型

                    }else{

                        newobj[k] = item

                    }

                }

            }

            deepCopy(o, obj)

            console.log(o);