深拷贝的三种实现方式

let obj1 = {  a: 0,
              b: {
                 c: undefined
                 }
            };
let obj2 = JSON.parse(JSON.stringify(obj1));
obj1.a = 1;
obj1.b.c = 1;
console.log(obj1); // { a: 1, b: { c: 1 } }
console.log(obj2); // { a: 0, b: {} }

npm i lodash//先安装

var _ = require('lodash');
var obj1 = {
    a: 1,
    b: { f: { g: 1 } },
    c: [1, 2, 3]
};
var obj2 = _.cloneDeep(obj1);
console.log(obj1 === obj2);// false地址不同

function deepCopy(object){
      if(!object || typeof object !== 'object')
      return;
      let newObject = Array.isArray(object) ? [] : {};
        //遍历对象中的key
      for(let key in object){
        //判断对象中有该键值吗
        if(object.hasOwnProperty(key)){
            //如果键值是对象递归，如果不是，将这个这个键值存到数组中
          newObject[key] =
            typeof object[key] === "object" ? deepCopy(object[key]): object[key];
        }
      }
      return newObject;
    }
    let obj1 ={
      a:1,
      b:{
        c: undefined
      },
      sayHello(){
        console.log("nihao")
      }
    }
    let obj2 = deepCopy(obj1)
    console.log(obj2)