javascript - 在 Javascript 中访问私有(private)成员的公共(public)方法

Question

我希望能够在 Javascript 中创建一个对象，该对象具有可以访问该对象的私有(private)成员的公共(public)方法。但是，我听说每次创建对象时都声明公共(public)方法会产生开销，所以我宁愿避免这种开销。因此，例如，这段代码将执行我想要的操作:

function createMyObject(parameter) {
    var that = {};

    var privateVariable,
        privateMethod = function () { return 1; };

    that.publicVariable = 0;

    that.publicMethod = function () {
        privateVariable = privateMethod();
    }

    return that;
}

但每次有人调用 createMyObject 时，它都必须创建函数来设置公共(public)方法。相反，如果我这样做:

function MyClass(parameter) {
    var privateVariable,
        privateMethod = function () { return 1; };

    this.publicVariable = 0;
}

MyClass.prototype.publicMethod = function () {};

在这里，我可以避免每次构造对象时都必须创建新函数来设置公共(public)方法，但这些公共(public)方法无法访问对象的私有(private)成员。

有没有什么方法可以避免每次构造对象时都必须为公共(public)方法创建新函数的开销，同时又能让它们访问私有(private)成员？

Answer 1

不，你不能。

能够访问私有(private)变量的公共(public)方法称为特权方法。

来自 Private Members in JavaScript , 道格拉斯·克罗克福德 (Douglas Crockford):

A privileged method is able to access the private variables and methods, and is itself accessible to the public methods and the outside. It is possible to delete or replace a privileged method, but it is not possible to alter it, or to force it to give up its secrets.

Privileged methods are assigned with this within the constructor.

然后，您不能使用原型(prototype)声明特权方法。