JavaScript 中实现私有属性的写类方式

/**
 * @param {String} className
 * @param {String/Function} superCls
 * @param {Function} classImp
 */
function $class(className, superCls, classImp){
    if(superCls === '') superCls = Object;
    function clazz(){
        if(typeof this.init == "function"){
            this.init.apply(this, arguments);
        }
    }
    var p = clazz.prototype = new superCls();
    var _super = superCls.prototype;
    window[className] = clazz;
    classImp.apply(p, [_super]);
}

/**
 * 父类 Person
 */
$class('Person','',function(){
    // 私有属性age
    var age;
    this.init = function(n, a){
        // 公有属性name
        this.name = n;
        // 私有属性初始化
        age = a;
    };
    this.getName = function(){
        return this.name;
    };
    this.setName = function(name){
        this.name = name;
    }
    this.getAge = function(){
        return age;
    };
    this.setAge = function(a){
        age = a;
    };
});

$class("Man",Person, function(supr){
    var school;
    this.init = function(n, a, s){
        supr.init.apply(this, [n,a]);
        school = s;
    }
    this.getSchool = function(){
        return school;
    };
    this.setSchool = function(s){
        school = s;
    };
});

var m = new Man('tom', 25, 'pku');
console.log(m.name); // tom 继承父类的共有属性name可以直接使用点操作符获取
console.log(m.age);  // undefined 父类的私有属性age不能直接使用点操作符获取
console.log(m.getAge()); // 25 可通过父类的共有方法getAge获取私有属性age
console.log(m.school); // undefined Man自己的私有属性仍然不能通过点操作符获取
console.log(m.getSchool()); // pku 通过getSchool()方法获取私有属性school