var parent = {

      lanage: "chinese"

  }

  var child = {

      name: "xxx",

      age: 12

  }

 function extend(parent, child) {

     var child = child || {};

     for (const propertype in parent) {

         child[propertype] = parent[propertype];

     }

 }

 extend(parent, child);

 console.log(child);//{ name: 'xxx', age: 12, lanage: 'chinese' }

var parent = {

      lanage: "chinese",

      address: {

          home: "gansu",

          office: "xian"

      },

      schools: ["xiaoxue", "zhongxue", "daxue"]

  }

 var child = {

     name: "xxx",

     age: 12

 }

 function extendDeeply(parent, child) {

     var child = child || {};

     for (const propertype in parent) {

         // 首先判断父对象的当前属性是不是引用类型

         if (typeof parent[propertype] === "object") {

             // 再判断该引用类型是不是数组，是则给子对象初始化为空数组，否则初始化为空对象

             child[propertype] = Array.isArray(parent[propertype]) ? [] : {};

             // 递归调用自己，将父对象的属性复制到子对象

             extendDeeply(parent[propertype], child[propertype]);

         } else {

             // 基本类型直接复制

             child[propertype] = parent[propertype];

         }

     }

 }

 extendDeeply(parent, child);

 console.log(child);

 child.schools[0] = "qinghua"; // 改变子对象的属性值

 child.address.home = "tianjin";

 console.log(child.schools[0]); //qinghua

 console.log(parent.schools[0]); //xiaoxue

 console.log(child.address.home); //tianjin

 console.log(parent.address.home); //gansu

function Parent() {

      this.name = "name";

      this.age = 12;

  }

  function Child() {

      Parent.call(this);

      this.language = "chinese";

  }

 var child = new Child();

 console.log(child);//{ name: 'name', age: 12, language: 'chinese' }

 child.name = "swk";

 console.log(new Parent().name);//name

var person = {name: "pname"};

  function myCreate(person) {

      var ins;

      function F() { };

      F.prototype = person;

      ins = new F();

      return ins;

  }

 var c = new myCreate(person);

 console.log(c.name); //pname

 console.log(c); //{}