process-eventemitter

Why?

This module implements the 'distributed-eventemitter' API for the browser or single node processes. Intended for non-distributed deployments or development.

Quick Start

var EventEmitter = require('process-eventemitter');
var events = new EventEmitter(); 
 
events.on('email.send', (message, resolve, reject) => {
  console.log('sending email...');
  //... send email
  // ...
 
  resolve('sent');
});
 
 
// somewhere else in your code
events.emitToOne('email.send', {
  to: '[e-mail]',
  subject: 'Hello Node.js',
  body: 'Request/response feature is just awesome...'
}, 3000).then((response) => {
  if ('sent' === response) {
    console.log('email was sent!');
  }
}).catch(console.log.bind());

Example using ES6 generators

"use strict";
 
const co = require('co');
co(function* () {
    try {
        let response = yield events.emitToOne('email.send', {
            to: '[e-mail]',
            subject: 'Hello Node.js',
            body: 'Request/response feature is just awesome...'
        }, 3000);
 
        if ('sent' === response) {
            console.log('email was sent!');
        }
    } catch (error) {
        console.log('error: ' + error);
    }
});

Requirements

• None

Installation

$ npm install process-eventemitter

Features

The same 'distributed-eventemitter' module API, but restricted to a single process and emitter instance. The methods 'connect', 'disconnect' are just kept for compatibility, in case you want to make your code distributed later ;)

Internal events

events.on('connected', (emitterId) => {
    // triggered when the emitter has been connected
});
 
events.on('disconnected', (emitterId) => {
    // triggered when the emitter has been disconnected
});
 
events.on('error', (error) => {
   // triggered when an internal error occurs 
}):
 
events.on('request', (event, request, raw) => {
   // triggered before invoke a listener using emitToOne feature
   
   // request data filtering and modification is allowed
   // example:
   request.data = ('string' === typeof request.data) ? request.data.toUpperCase() : request.data
}):
 
events.on('response', (event, response, raw) => {
   // triggered after invoke a listener using emitToOne feature
   
   // response data filtering and modification is allowed
   // example:
   if (response.ok)
     response.data = ('string' === typeof response.data) ? response.data.toUpperCase() : response.data
   else 
     console.log('error ocurred: ' + response.data.message);
}):
 

API

getId: Get the emitter instance unique id.

events.getId(); // UUID v4 value

connect: Does nothing. Kept for compatilibity with the distributed version.

events.connect().then(()=> {
  console.log('connected');
});

disconnect:Does nothing. Kept for compatilibity with the distributed version.

events.disconnect().then(()=> {
  console.log('disconnected');
});

emitToOne: Notify a custom event to only one target listener. The method accept only one argument as event data.

events.on('my.event', (data, resolve, reject) => {
  if ('hello' === data){
    resolve('world');
  } else {
    reject('invalid args');
  }
});
 
// calling without timeout
events.emitToOne('my.event', 'hello').then((response) => {
  console.log('world' === response);
});
 
// calling with timeout (ms)
events.emitToOne('my.event', {data: 'hello'}, 100).catch((error) => {
  console.log('invalid args' === error);
});

Tests

$ npm install
$ npm test