7 浅拷贝和深拷贝

一、简单数据类型

浅拷贝：newArr = arr
// 简单的赋值
        var arr = [1,2,3,4];
        var newArr = arr;
        newArr.push(5)
        console.log(arr);//[1,2,3,4,5]

深拷贝：newArr
<script>
        // 浅拷贝：指向的是堆内存的通风一个对象
         //深拷贝：指向堆内存的不同对象
     1、扩展
        var arr = [1,2,3,4];
        var newArr = [...arr];
        newArr.push(5)
        console.log(arr);//[1,2,3,4]
    2、slice
         var arr = [1,2,3,4];
         var newArr = arr.slice(0,);
         arr.push(5)
         console.log(arr);//[1,2,3,4]
    3、concat
        var arr = [1,2,3,4]
        var newArr = [].concat(arr)
        newArr.push(5);
        console.log(arr);//[1,2,3,4]
</script>

二、复杂数据类型

//浅拷贝
<script>
        var arr = [{name:"lisi"},{name:"wangwu"}]
        var newArr = [...arr]
        arr[0].name = "react";
        console.log(arr);
    </script>

JSON.parse JSON.stringify实现

//深拷贝 JSON.parse JSON.stringify
<script>
        var arr = [{name:"lisi"},{name:"wangwu"}];
        var newArr = JSON.parse(JSON.stringify(arr));
        arr[0].name = "react"
        console.log(newArr);
    </script>

算法实现

<script>
        var arr = [{name:"lisi"},{name:"wangwu"}];
        function deepClone(obj){
            //如果是初始值 直接返回
            let result;
            if(obj instanceof Array){
                 result = []
            }else if(typeof obj =="object"){
                result = {}
            }else{
                return obj
            }
            for(let key in obj){
                result[key] = deepClone(obj[key])
            }
            return result
        }
        var newArr = deepClone(arr)
        arr[0].name = "react"
        console.log(newArr);
    </script>