javascript - 私有(private)对象属性

Question

我有一个 RequireJs 模块，它实例化了另一个模块并代理了它的一些方法。我现在想隐藏模块实例本身，只允许通过代理方法进行访问。

define(['mediator'], function(Mediator) {

  var Proxy;

  Proxy = function(prefix) {
    this.prefix = prefix;
    this.mediator = new Mediator();
  };

  Proxy.prototype.on = function(event, callback, context) {
    this.mediator.subscribe(this.prefix + event, callback, context || this);
  };

  Proxy.prototype.off = function(event, callback, context) {
    this.mediator.unsubscribe(this.prefix + event, callback, context || this);
  };

  Proxy.prototype.trigger = function() {
    arguments[0] = this.prefix + arguments[0];
    this.mediator.trigger.apply(this.mediator, arguments);
  };

  return Proxy;

});

require(['proxy'], function(Proxy) {

  var proxy = new Proxy('sample:');

  // this access is secured and bound to the prefix
  // I cannot mess up with other events which do not belong to me
  proxy.on('log', function(message) { console.log(message); });
  proxy.trigger('log', 'hi hello');

  // unfortunately there still would be a hack to leave my event scope
  proxy.mediator.trigger('outerscope:test', 'blabla');

});

如您所见，可以访问代理原型(prototype)的内部使用的中介对象并将其搞砸......

我现在想以某种方式隐藏调解器实例，但不知道在哪里。我可以将它存储在 requirejs 模块回调内的某个普通变量中，但这不适用于 requirejs 并且可能导致重叠。

那我还能做什么呢？

更新:

define(['mediator'], function(Mediator) {

  var Proxy;

  var mediator = new Mediator();

  Proxy = function(prefix) {
    this.prefix = prefix;
  };

  Proxy.prototype.on = function(event, callback, context) {
    mediator.subscribe(this.prefix + event, callback, context || this);
  };

  Proxy.prototype.off = function(event, callback, context) {
    mediator.unsubscribe(this.prefix + event, callback, context || this);
  };

  Proxy.prototype.trigger = function() {
    arguments[0] = this.prefix + arguments[0];
    mediator.trigger.apply(this.mediator, arguments);
  };

  return Proxy;

});

require(['proxy'], function(Proxy) {

  var proxy = new Proxy('sample:');
  proxy.on('log', function(message) { console.log(message); });

});

Answer 1

这是一个典型的Javascript闭包封装变量的例子。您需要将中介实例定义为与 Proxy 处于同一范围内的局部变量。这将允许 Proxy 对象通过闭包访问 Mediator，但会将 Mediator 与定义回调之外的代码隔离开来。所以像这样:

define(['mediator'], function(Mediator) {

    // Make mediator local scope variable
    var mediator = new Mediator(),

    Proxy = function(prefix) {
        this.prefix = prefix;
    };

    Proxy.prototype.on = function(event, callback, context) {
        mediator.subscribe(this.prefix + event, callback, context || this);
    };

    // ... rest of the code

    return Proxy;

});