new 一个对象

function Person(name, age) {  	this.name = name;  	this.age = age;   }  var person = new Person("hellen", 23);

 

1、创建一个空对象

var obj = new Object();

2、让Person中的this指向obj，并执行Person的函数体

var result = Person.apply(obj,arguments);

3、设置原型链，将obj的__proto__成员指向了Person函数对象的prototype成员对象

obj.__proto__ = Person.prototype;

4、判断Person的返回值类型，如果是值类型，返回obj。如果是引用类型，就返回这个引用类型的对象。

if (typeof(result) == "object") 	person = result;  else	person = obj;

 

function Person (name, age) {  this.name = name;  this.age = age;}Person.prototype.sayName = function () {  console.log(this.name);};var person = new Person('Hellen', 23);person.sayName();console.log(person instanceof Person);function New () {  let obj = new Object();  let fn = [].shift.call(arguments);  let args = arguments;  var ret = fn.apply(obj, args);  obj.__proto__ = fn.prototype;  return typeof ret === 'object' ? ret : obj;}let person1 = New(Person, 'Bob', 23);person1.sayName();console.log(person1 instanceof Person);