node.js eventEmitter:监听文件中的事件 [英] node.js eventEmitter : Listen for events across files

问题描述

刚开始使用Node.js时，我有以下查询:

Just getting started on Node.js, I have the following query:

我的server.js文件中包含以下javascript:

I have a following javascript in my server.js file:

================================================ =====

====================================================

function onRequest(request, response) {
  var pathname = url.parse(request.url).pathname;
  route(handle, pathname, response);
  console.log("Request for " + pathname + " received.");
}

var server = http.createServer(onRequest)
server.listen(8888);
console.log("Server started")

================================================ ================

===============================================================

我还有另一个js文件，我想在其中注册服务器发出的监听"事件或服务器发出的任何事件的侦听器.

I have another js file, where I want to register a listener for the "listening" event emitted by server, or for that matter any event that is emitted by server.

我无法更改原始文件以导出服务器对象.

I cannot change the original file to export the server object.

有什么办法可以实现我的目标?

Is there any way I can achieve my objective ?

推荐答案

您将希望像下面那样将服务器对象传递到另一个模块中，或者想要在另一个模块上公开一个函数，然后在父模块中指定为侦听器.无论哪种方式都行得通.这仅取决于您希望.on调用的位置.

You'll want to either pass the server object into your other module like below or you'll want to expose a function on your other module that you can then assign as a listener in the parent module. Either way would work. It just depends where you want the .on call to be.

// app.js

var otherModule = require('./other-module.js');

function onRequest(request, response) {

  var pathname = url.parse(request.url).pathname;
  route(handle, pathname, response);

  console.log("Request for " + pathname + " received.");
}

var server = http.createServer(onRequest);
otherModule.init(server);
server.listen(8888, function () {
  console.log("Server started");
}); // <-- Passing in this callback is a shortcut for defining an event listener for the "listen" event.

---

// other-module.js

exports.init = function (server) {
  server.on('listen', function () {
    console.log("listen event fired.");
  });
};

在上面的示例中，我为listen事件设置了两个事件侦听器.当我们将回调函数传递给server.listen时，第一个被注册.这只是执行server.on('listen', ...)的快捷方式.第二个事件处理程序显然是在other-module.js中设置的:)

In the above example I setup two event listeners for the listen event. The first one is registered when we pass in a callback function to server.listen. That's just a shortcut for doing server.on('listen', ...). The second event handler is setup in other-module.js, obviously :)

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