要创建一个带有公共方法的JavaScript类,我可以这样做:

function Restaurant() {}

Restaurant.prototype.buy_food = function(){
   // something here
}

Restaurant.prototype.use_restroom = function(){
   // something here
}

这样,我类的用户就可以:

var restaurant = new Restaurant();
restaurant.buy_food();
restaurant.use_restroom();

如何创建一个私有方法,可以由buy_food和use_restroom方法调用,但不能由类的用户外部调用?

换句话说,我希望我的方法实现能够做到:

Restaurant.prototype.use_restroom = function() {
   this.private_stuff();
}

但这是行不通的:

var r = new Restaurant();
r.private_stuff();

如何将private_stuff定义为私有方法,使两者都成立?

我读过Doug Crockford的文章几次,但它似乎不像“私有”方法可以被公共方法调用,而“特权”方法可以被外部调用。


当前回答

我已经创建了一个新工具,允许您在原型上拥有真正的私有方法 https://github.com/TremayneChrist/ProtectJS

例子:

var MyObject = (function () {

  // Create the object
  function MyObject() {}

  // Add methods to the prototype
  MyObject.prototype = {

    // This is our public method
    public: function () {
      console.log('PUBLIC method has been called');
    },

    // This is our private method, using (_)
    _private: function () {
      console.log('PRIVATE method has been called');
    }
  }

  return protect(MyObject);

})();

// Create an instance of the object
var mo = new MyObject();

// Call its methods
mo.public(); // Pass
mo._private(); // Fail

其他回答

就我个人而言,我更喜欢用JavaScript创建类的以下模式:

var myClass = (function() {
    // Private class properties go here

    var blueprint = function() {
        // Private instance properties go here
        ...
    };

    blueprint.prototype = { 
        // Public class properties go here
        ...
    };

    return  {
         // Public class properties go here
        create : function() { return new blueprint(); }
        ...
    };
})();

如您所见,它允许您定义类属性和实例属性,每个属性都可以是公共的和私有的。


Demo

var Restaurant = function() { var totalfoodcount = 0; // Private class property var totalrestroomcount = 0; // Private class property var Restaurant = function(name){ var foodcount = 0; // Private instance property var restroomcount = 0; // Private instance property this.name = name this.incrementFoodCount = function() { foodcount++; totalfoodcount++; this.printStatus(); }; this.incrementRestroomCount = function() { restroomcount++; totalrestroomcount++; this.printStatus(); }; this.getRestroomCount = function() { return restroomcount; }, this.getFoodCount = function() { return foodcount; } }; Restaurant.prototype = { name : '', buy_food : function(){ this.incrementFoodCount(); }, use_restroom : function(){ this.incrementRestroomCount(); }, getTotalRestroomCount : function() { return totalrestroomcount; }, getTotalFoodCount : function() { return totalfoodcount; }, printStatus : function() { document.body.innerHTML += '<h3>Buying food at '+this.name+'</h3>' + '<ul>' + '<li>Restroom count at ' + this.name + ' : '+ this.getRestroomCount() + '</li>' + '<li>Food count at ' + this.name + ' : ' + this.getFoodCount() + '</li>' + '<li>Total restroom count : '+ this.getTotalRestroomCount() + '</li>' + '<li>Total food count : '+ this.getTotalFoodCount() + '</li>' + '</ul>'; } }; return { // Singleton public properties create : function(name) { return new Restaurant(name); }, printStatus : function() { document.body.innerHTML += '<hr />' + '<h3>Overview</h3>' + '<ul>' + '<li>Total restroom count : '+ Restaurant.prototype.getTotalRestroomCount() + '</li>' + '<li>Total food count : '+ Restaurant.prototype.getTotalFoodCount() + '</li>' + '</ul>' + '<hr />'; } }; }(); var Wendys = Restaurant.create("Wendy's"); var McDonalds = Restaurant.create("McDonald's"); var KFC = Restaurant.create("KFC"); var BurgerKing = Restaurant.create("Burger King"); Restaurant.printStatus(); Wendys.buy_food(); Wendys.use_restroom(); KFC.use_restroom(); KFC.use_restroom(); Wendys.use_restroom(); McDonalds.buy_food(); BurgerKing.buy_food(); Restaurant.printStatus(); BurgerKing.buy_food(); Wendys.use_restroom(); McDonalds.buy_food(); KFC.buy_food(); Wendys.buy_food(); BurgerKing.buy_food(); McDonalds.buy_food(); Restaurant.printStatus();

看看这小提琴。

私有函数不能使用模块模式访问公共变量

你可以像这样模拟私有方法:

function Restaurant() {
}

Restaurant.prototype = (function() {
    var private_stuff = function() {
        // Private code here
    };

    return {

        constructor:Restaurant,

        use_restroom:function() {
            private_stuff();
        }

    };
})();

var r = new Restaurant();

// This will work:
r.use_restroom();

// This will cause an error:
r.private_stuff();

更多关于此技术的信息,请访问:http://webreflection.blogspot.com/2008/04/natural-javascript-private-methods.html

ES12私有方法

现在你可以使用es12私有方法来实现这一点。您只需要在方法名之前添加一个#。

class ClassWithPrivateMethod {
  #privateMethod() {
    return 'hello world';
  }

  getPrivateMessage() {
    return #privateMethod();
  }
}

一般来说,我将私有Object _临时添加到对象中。 您必须在该方法的“Power-constructor”中显式地打开隐私。 如果您从原型中调用该方法,您将会 能够覆盖原型方法

使一个公共方法在"Power-constructor"中可访问:(ctx是对象上下文) ctx。test = GD.Fabric。(“测试”,GD.Test开放。原型,ctx, _);//是私有对象 现在我有这个openPrivacy: GD.Fabric.openPrivacy = function(func, clss, ctx, _) { 返回函数(){ ctx。_ = _; Var res = clss[func]。应用(ctx、参数); ctx。_ = null; 返回res; }; };