javascript - Private V.S. 令人困惑的例子 书中的公共(public)方法？

Question

我最近一直在阅读 Stefanov 的《Javascript 模式》。我发现这个例子让我感到困惑:

Another case of using a convention to mimic functionality is the private members >con- vention. Although you can implement true privacy in JavaScript, sometimes >evelopers find it easier to just use an underscore prefix to denote a private >method or property. Consider the following example:

var person = {

getName: function () {

return this._getFirst() + ' ' + this._getLast(); },

_getFirst: function () {

// ... },

_getLast: function () {

// ... }

};

In this example getName() is meant to be a public method, part of the stable API,

whereas _getFirst() and _getLast() are meant to be private.

据我了解，方法是私有(private)的还是公共(public)的，都是由它的编写方式定义的。例如，如果我们谈论构造函数，那么“this.getFirst() = function(){ ... }”将是一个公共(public)方法，而“var getFirst=function(){...}”将是私有(private)的。

书中的示例不是构造函数。我确实相信人们不能简单地使用下划线将方法设为公共(public)或私有(private)。那么，我们如何在像上面例子那样声明的对象中创建私有(private)或公共(public)方法呢？

非常感谢!

Answer 1

Javascript 没有真正的私有(private)变量/方法。模式(下划线)只是编码约定。请参阅MDN: Private properties 。上面写着

The above technique (underscoring) is simple and clearly expresses intent. However, the use of an underscore prefix is just a coding convention and is not enforced by the language: there is nothing to prevent a user from directly accessing a property that is supposed to be private.

同时，您不能在 Object Literal {...} 构造中使用 var getFirst=function(){...}。