构造函数忘记new? 看这里看这里

方法一：自调用构造函数

 function Person(name){
     if( !(this instanceof Person)){//一定要放在开头。检查this是否为构造函数的一个实例
         return new Person(name);//自调用，会通通走一遍，不用担心后面的属性没加上
     }
     this.name = name;
     this.love = true;
 }
 Person.prototype.sayHello = function(){
     console.log('hi, '+ this.name);
 }

 var per1 = new Person('wqh');
 var per2 = Person('czm');
 console.log(per1.name);//wqh
 console.log(per1.love);//true
 console.log(per2.name);//wqh
 console.log(per2.love);//true
 per1.sayHello();//hi, wqh
 per2.sayHello();//hi, czm

方法二：使用that

 function Person(name){
     var that = Object.create(Person.prototype);//手工指定原型
     that.name = name;
      that.love = true;
     return that;//返回that
 }
 Person.prototype.sayHello = function(){
     console.log('hi, '+ this.name);
 }

 var per1 = Person('wqh');
 var per2 = new Person('czm');
 console.log(per1.name);//wqh
 console.log(per1.love);//true
 per1.sayHello();//hi, wqh
 console.log(per2.name);//czm
 console.log(per1.love);//true
 per2.sayHello();//hi, czm

显然，我更倾向于第一种(*^__^*)

参考《javaScript模式》P47~P49，并稍作修改