NodeJS EventEmiter not emiting the event

Asked Jul 14 '16 at 18:01

Active Jul 14 '16 at 18:01

Viewed 26 times

I just wonder if the following code is supposed to work:

// my-class.js

const EventEmmiter = require('events')

class MyClass extends EventEmmiter {
  constructor () {
    super()
  }

  trigger () {
    console.log('trigger')
    this.emit('foo')
  }
}

module.exports = MyClass


// test.js
const MyClass = new (require('./my-class'))

MyClass.trigger()

MyClass.on('foo', () => {
  console.log('event emited')
})

// result: "trigger"

As you can see, the even handler MyClass.on('foo') doesn't get called. Is there a way to register event listeners outside of the file emitting the event?

asked Jul 14 '16 at 18:01

Andrei Stalbe

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3

Can you subscribe before you emit the vent? – Vsevolod Goloviznin Jul 14 '16 at 18:02
3

@VsevolodGoloviznin they _should_ subscribe before they emit, even. `EventEmitter` is synchronous. – robertklep Jul 14 '16 at 18:02
What you mean by that? I can register a listener inside the `constructor` and it get's called, this I know for sure. – Andrei Stalbe Jul 14 '16 at 18:03
1

@AndreiStalbe in that case, you are registering a listener _before_ the event is emitted. In your example code, it's the other way around: you emit, _then_ you subscribe. That's the wrong order. – robertklep Jul 14 '16 at 18:04
@robertklep Oh oh, this make complete sense now. I must have missed this bit of information in the Node documentation. – Andrei Stalbe Jul 14 '16 at 18:05

NodeJS EventEmiter not emiting the event

0 Answers0