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] = 100
console.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()) //10
console.log(copyObj2.getNum()) //单身狗

其他方法;

一、假如你用jquery，可以使用$.extend()

亲测均有效

var copyarr = $.extend(true, [], arr1);
copyarr[1] = "888"

console.log(copyarr); //[1,888,3,4,5,六,七]
console.log(arr1); //[1,2,3,4,5,六,七]

var copyarr = $.extend(true, {}, obj2);
copyarr.getNum = function(){
return "这是测试"
}

console.log(copyarr.getNum()); //这是测试
console.log(obj2.getNum()); //10