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A repository of global listeners notified about every step of Prototype-based Ajax requests

有时候，你需要提供所有的Ajax操作发生页面上通过的Ajax.Request，Ajax.Updater的或Ajax.PeriodicalUpdater通用行为。

例如，您可能希望自动显示指标正在进行时，一个Ajax请求，并隐藏它时都不是。你可能要分解出的异常处理以及在登录页面上自定义时尚的某处。有无数的可能性。

为了实现这一目标， prototype提供Ajax.Responders，它可以让你注册（并且，如果您愿意，后来注销）的反应，这是具有特别的命名方法的对象。这些名字来自一组对应于不同时间点（或成果）的一个Ajax请求的生命周期一般回调。

例如，原型自动注册，保持一个漂亮的变量：Ajax.activeRequestCount一个响应。这意味着，在特定的时间，目前活跃的Ajax请求的数量 - 通过监测他们的onCreate的onComplete事件。此代码是相当简单：

Ajax.Responders.register({   onCreate: function() {     Ajax.activeRequestCount++;   },   onComplete: function() {     Ajax.activeRequestCount--;   } });

Responder callbacks

The callbacks for responders are similar to the callbacks described in the Ajax, but take a different signature. They're invoked with three parameters: the requester object (i.e., the corresponding "instance" of Ajax.Request), the XMLHttpRequest object, and the result of evaluating the X-JSON response header, if any (can be null). They also execute in the context of the responder, bound to the this reference.

• onCreate: Triggered whenever a requester object from the Ajax namespace is created, after its parameters are adjusted and before its XHR connection is opened. This takes two arguments: the requester object and the underlying XHR object.
• onUninitialized (Not guaranteed): Invoked just after the XHR object is created.
• onLoading (Not guaranteed): Triggered when the underlying XHR object is being setup, and its connection opened.
• onLoaded (Not guaranteed): Triggered once the underlying XHR object is setup, the connection is open, and it is ready to send its actual request.
• onInteractive (Not guaranteed): Triggered whenever the requester receives a part of the response (but not the final part), should it be sent in several packets.
• onException: Triggered whenever an XHR error arises. Has a custom signature: the first argument is the requester (i.e. an Ajax.Request instance), and the second is the exception object.
• onComplete: Triggered at the very end of a request's life-cycle, after the request completes, status-specific callbacks are called, and possible automatic behaviors are processed. Guaranteed to run regardless of what happened during the request.

Prototype