你可以这样做，但缺点是它不能成为原型的一部分:

function Restaurant() {
    var myPrivateVar;

    var private_stuff = function() {  // Only visible inside Restaurant()
        myPrivateVar = "I can set this here!";
    }

    this.use_restroom = function() {  // use_restroom is visible to all
        private_stuff();
    }

    this.buy_food = function() {   // buy_food is visible to all
        private_stuff();
    }
}

以下是迄今为止我最喜欢的关于javascript中的私有/公共方法/成员和实例化:

这是文章:http://www.sefol.com/?p=1090

下面是一个例子:

var Person = (function () {

    //Immediately returns an anonymous function which builds our modules 
    return function (name, location) {

        alert("createPerson called with " + name);

        var localPrivateVar = name;

        var localPublicVar = "A public variable";

        var localPublicFunction = function () {
            alert("PUBLIC Func called, private var is :" + localPrivateVar)
        };

        var localPrivateFunction = function () {
            alert("PRIVATE Func called ")
        };

        var setName = function (name) {

            localPrivateVar = name;

        }

        return {

            publicVar: localPublicVar,

            location: location,

            publicFunction: localPublicFunction,

            setName: setName

        }

    }
})();


//Request a Person instance - should print "createPerson called with ben"
var x = Person("ben", "germany");

//Request a Person instance - should print "createPerson called with candide"
var y = Person("candide", "belgium");

//Prints "ben"
x.publicFunction();

//Prints "candide"
y.publicFunction();

//Now call a public function which sets the value of a private variable in the x instance
x.setName("Ben 2");

//Shouldn't have changed this : prints "candide"
y.publicFunction();

//Should have changed this : prints "Ben 2"
x.publicFunction();

JSFiddle: http://jsfiddle.net/northkildonan/kopj3dt3/1/

我认为这样的问题一次又一次地出现是因为缺乏对闭包的理解。Сlosures是JS中最重要的东西。每个JS程序员都必须感受到它的本质。

1. 首先，我们需要创建单独的作用域(闭包)。

function () {

}

2. 在这个领域，我们想做什么就做什么。没人会知道的。

function () {
    var name,
        secretSkills = {
            pizza: function () { return new Pizza() },
            sushi: function () { return new Sushi() }
        }

    function Restaurant(_name) {
        name = _name
    }
    Restaurant.prototype.getFood = function (name) {
        return name in secretSkills ? secretSkills[name]() : null
    }
}

3.为了让全世界知道我们的餐厅班， 我们必须从闭包中返回它。

var Restaurant = (function () {
    // Restaurant definition
    return Restaurant
})()

4. 最后，我们有:

var Restaurant = (function () {
    var name,
        secretSkills = {
            pizza: function () { return new Pizza() },
            sushi: function () { return new Sushi() }
        }

    function Restaurant(_name) {
        name = _name
    }
    Restaurant.prototype.getFood = function (name) {
        return name in secretSkills ? secretSkills[name]() : null
    }
    return Restaurant
})()

5. 此外，这种方法具有继承和模板的潜力

// Abstract class
function AbstractRestaurant(skills) {
    var name
    function Restaurant(_name) {
        name = _name
    }
    Restaurant.prototype.getFood = function (name) {
        return skills && name in skills ? skills[name]() : null
    }
    return Restaurant
}

// Concrete classes
SushiRestaurant = AbstractRestaurant({ 
    sushi: function() { return new Sushi() } 
})

PizzaRestaurant = AbstractRestaurant({ 
    pizza: function() { return new Pizza() } 
})

var r1 = new SushiRestaurant('Yo! Sushi'),
    r2 = new PizzaRestaurant('Dominos Pizza')

r1.getFood('sushi')
r2.getFood('pizza')

我希望这能帮助人们更好地理解这个主题

这个呢?

var Restaurant = (function() {

 var _id = 0;
 var privateVars = [];

 function Restaurant(name) {
     this.id = ++_id;
     this.name = name;
     privateVars[this.id] = {
         cooked: []
     };
 }

 Restaurant.prototype.cook = function (food) {
     privateVars[this.id].cooked.push(food);
 }

 return Restaurant;

})();

在直接函数的作用域之外查找私有变量是不可能的。 没有重复的函数，节省内存。

缺点是私有变量的查找非常笨拙。“煮熟了”这个词很可笑。还有一个额外的“id”变量。

在这些情况下，当你有一个公共API，并且你想要私有和公共的方法/属性时，我总是使用模块模式。这个模式在YUI库中很流行，详细信息可以在这里找到:

http://yuiblog.com/blog/2007/06/12/module-pattern/

它非常简单明了，其他开发人员也很容易理解。举个简单的例子:

var MYLIB = function() {  
    var aPrivateProperty = true;
    var aPrivateMethod = function() {
        // some code here...
    };
    return {
        aPublicMethod : function() {
            aPrivateMethod(); // okay
            // some code here...
        },
        aPublicProperty : true
    };  
}();

MYLIB.aPrivateMethod() // not okay
MYLIB.aPublicMethod() // okay

你必须在你实际的构造函数周围放一个闭包，在那里你可以定义你的私有方法。 要通过这些私有方法改变实例的数据，你必须给它们一个"this"，要么作为函数参数，要么用.apply(this)调用这个函数:

var Restaurant = (function(){
    var private_buy_food = function(that){
        that.data.soldFood = true;
    }
    var private_take_a_shit = function(){
        this.data.isdirty = true;   
    }
    // New Closure
    function restaurant()
    {
        this.data = {
            isdirty : false,
            soldFood: false,
        };
    }

    restaurant.prototype.buy_food = function()
    {
       private_buy_food(this);
    }
    restaurant.prototype.use_restroom = function()
    {
       private_take_a_shit.call(this);
    }
    return restaurant;
})()

// TEST:

var McDonalds = new Restaurant();
McDonalds.buy_food();
McDonalds.use_restroom();
console.log(McDonalds);
console.log(McDonalds.__proto__);