Issue events from module Nodejs

Question

Issue events from module Nodejs

Navigation

#1 by (2 votes)

1

Greetings, I am trying to issue an event in nodejs from a separate module, but I can not capture it, I have this code in the module

var util = require("util");
var events = require("events");

function MyStream (connection) {

if (!(this instanceof MyStream))
    return new MyStream(connection);
  events.EventEmitter.call(this); 

  var self = this;
  self.emit('pulse', 'client pulse');     

}

util.inherits(MyStream, events.EventEmitter);

exports.MyStream = MyStream;

and then from the main script I try to capture the event but I can not capture it

var server = require("./server");

var mystream = server.MyStream('aqui van los parametros');

mystream.on('pulse', function  (data) {
    console.log(data);
});

I'm not getting any errors either, any ideas? thanks

javascript nodejs

asked by danielvkp 20.06.2016 в 01:21

source

1 answer

How to make an if in linq How to put in my table in JSON jQuery a sql pdf?

score 2 · Accepted Answer

You have two problems in your code

The names of the events do not match. On the one hand, you broadcast a event and on the other hand you try to capture the join event. Instead of:

self.emit('pulse', ....
........
mystream.on('join', ....

It should be

self.emit('pulse', ....
........
mystream.on('pulse', ....

The names of the events that are broadcast and captured must match.

You are trying to issue the event within the same constructor of the object. This will cause that when you finish the setup of your event handler the event has already been broadcast and your code will not capture it anyway.

var mystream = server.MyStream('aqui van los parametros');
// Cuando llegas a esta línea de código ya el evento se ha emitido
mystream.on('join', ..........

To prove this point, just set a timeout inside the constructor of your object and you will see the event emit without problems. This is a replacement for your server.js

file

function MyStream (connection) {
    // Es una buena práctica ponerle llaves a todos tus bloques aunque sean de una sola línea
    // Lee http://jshint.com/docs/options/#curly
    if (!(this instanceof MyStream)) {
        return new MyStream(connection);
    }
    events.EventEmitter.call(this);

    var self = this;

    // Este código es sólamente para una demostración
    setTimeout(function () {
        self.emit('pulse', 'client pulse');
    }, 3000);
}

And for the other file

 var server = require("./server");

 var mystream = server.MyStream('aqui van los parametros');

 mystream.on('pulse', function  (data) {
     console.log(data);
 });

And the result is shown in the photo