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