2. function myNew(Obj, ...args) {
    3.      let obj = Object.create(Obj.prototype);//使用指定的原型对象及其属性去创建一个新的对象
    4.      let ret = Obj.apply(obj,args); // 绑定 this 到obj, 设置 obj 的属性
    5.      if ((typeof ret === "object" || typeof ret === "function") && ret !== null) {
    6.        return ret;
    7.      }
    8.      return obj; //确保构造器总是返回一个对象
    9. }
    10. function Foo(name, age) {
    11.    this.name = name;
    12.    this.age = age
    13. }
    15. let tom = new Foo('tom', 18)  // {name: "tom", age: 18}
    16. let kim = myNew(Foo, 'kim', 20) //{name: "kim", age: 20}