Javascript Constructor，Why it sh

参考：Javascript Constructors- Why it should be used- Object Oriented Programming in Javascript

1.首先假设你需要创建一个classmate对象，它需要用name，age，city三个属性：

var classmate1 = {};
classmate1.name = 'Gerg';
classmate1.age = 21;
classmate1.city = 'Shanghai';

2.同学asan说：帮我也创建一个对象呗。好勒

var classmate2 = {};
classmate2.name = 'asan';
classmate2.age = 22;
classmate2.city = 'dadongbei';

3.剩下40个学生一看：来来来，一人创一个呗。好勒

//其实我内心是拒绝的，想想，有什么办法可以不用重复上面的动作40遍？
//bingo----我有个朋友叫函数，请它帮帮忙

function createClassmateObject(name,age,city){
    var classmate = {};
    classmate.name = name;
    classmate.age = age;
    classmate.city = city;
    return classmate;
}
var classmate3 = createClassmateObject('qin','23','hlj');

4.这个时候班主任一看：这玩意不错，来来来，帮老师们都弄份，不多，一共200个人。

//呵呵，no problem
//每次创建一个对象，返回一个对象也忒烦了，有没有省事点的方法？
//bingo-----构造函数

function createTeacherObject(name,age,city){
    this.name = name;
    this.age = age;
    this.city = city;
}
var teacher1 = createTeacherObject('lalala',35,'gz');
teacher1;
>>>undefined

5.不对呀，怎么返回undefined呀。

//bingo----好像漏了个new
function createTeacherObject(name,age,city){
    this.name = name;
    this.age = age;
    this.city = city;
}
var teacher1 = new createTeacherObject('lalala',35,'gz');
teacher1;
>>>createTeacherObject {name: "lalala", age: 35, city: "gz"}

6.注意，返回的是一个对象喔

JavaScript Constructor functions automatically returns the object after it is populated.