一、理解深拷贝与浅拷贝
如下代码，把 a 的值赋给 b ，修改 b 的值会直接修改到 a 的值，这叫浅拷贝。（其实他们修改的是同一个对象）
var a = [1,2,3,4,5];var b = a;b[2] = 100;console.log(a); ?????????//[1,2,100,4,5]console.log(b);//[1,2,100,4,5] ???
把 obj1 的值赋给 obj2 ，修改 obj2 的值，不会影响到 obj1 的值 ，这叫深拷贝
var obj1 = [1,2,3,4,5]var obj2 = [];for(var i = 0; i < obj1.length; i++){obj2.push(obj1[i])}obj2[2] = 100console.log(obj1); ?????//[1,2,3,4,5]console.log(obj2) ??????//[1,2,100,4,5]
二、深度拷贝的多种情况
这里我列举以下几种例子，在以下的拷贝方法里也会将各种方法做一个比较，例子如下
var obj1 = {name:"张三",age:18}var obj2 = {name:"王五",intersects:{one:"游泳",two:"看书"},getNum: function(){ return 10;},numArr:["猫","狗","鸡"]}var arr1 = [1,2,3,4,5,"六","七"]var arr2 = [{name:"张三",age:18},{name:"王五",age:19}]方法一：转为JSON格式
亲测：obj1，arr1，arr2 均有效，obj2无效，
原因：这种方法的缺陷是会破坏原型链，并且无法拷贝属性值为function的属性
var copyObj2 = JSON.parse(JSON.stringify(obj1))copyObj2.name = "哈哈"console.log(obj1) ???????//{name:"张三",age:18}console.log(copyObj2) //{name:"哈哈",age:18}方法二：采用递归的方式
亲测均有效
function copy(obj1, obj2) {var obj2 = obj2 || {};for(var name in obj1) {if(typeof obj1[name] === "object") {obj2[name] = (obj1[name].constructor === Array) ? [] : {};copy(obj1[name], obj2[name]);} else {obj2[name] = obj1[name];}}return obj2;}var copyObj2 = {}copyObj2 = copy(obj2,copyObj2);copyObj2.getNum = function(){return "单身狗"}console.log(obj2.getNum()) ???????//10console.log(copyObj2.getNum()) ?//单身狗
js数据处理-----数据拷贝
原文地址：https://www.cnblogs.com/qqing/p/9510631.html