如何在 node.js (express.js) 中创建自定义事件监听器？
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How to create custom event listener in node.js (express.js)?
提问by murvinlai
I have a giant function with a lot of nested callbacks. I want to make it cleaner and easier to handle. So, I'm thinking of using custom event listeners
我有一个带有很多嵌套回调的巨大函数。我想让它更干净，更容易处理。所以，我正在考虑使用自定义事件侦听器
Like, when a function is done, in the callback, instead of putting a chunk of code, it just emits an event, and then the listener will run.
就像，当一个函数完成时，在回调中，它只是发出一个事件，而不是放置一段代码，然后侦听器将运行。
So, how to do that in node.js? I am still looking for a good example to guide me through.
那么，如何在 node.js 中做到这一点？我仍在寻找一个很好的例子来指导我。
采纳答案by mjs
You probably want to create an EventEmitterobject, and call emit()on it.
您可能想要创建一个EventEmitter对象，并调用emit()它。
回答by StephaneP
You can set events like this
您可以设置这样的事件
app.on('event:user_created', callback);
Then you can emit them
然后你可以发出它们
app.emit('event:user_created', data);
express.jsuses EventEmitter.
express.js使用EventEmitter.
回答by Olumuyiwa akin-ogundeji
I just came across this question, I'd like to chip in my 2 cents, specifically responding to Luis.
我刚刚遇到这个问题，我想投入 2 美分，专门回答路易斯。
In Express, if you want the 'app' instance to listen for a custom event you would do something like:
在 Express 中，如果您希望 'app' 实例侦听自定义事件，您可以执行以下操作：
app.on('testEvent', function () {
return console.log('responded to testEvent');
});
app.get('/test', function (req, res) {
app.emit('testEvent');
return res.status(200).end();
});
Then when that route is hit, you'd see the response in the console. Of course you can implement this as you wish.
然后当该路由被命中时，您会在控制台中看到响应。当然，您可以根据需要实现它。
