event-emitter-object v4.0.4

Javascript Event Emitter Object

A simple event emitter object that you can plug into your javascript libraries.

API is very similar to the node.js events.

Install

npm install event-emitter-object

Import

There are different types of distributions depending on your use case. Essentially, the package can be imported via require:

const EventEmitterObject = require('event-emitter-object')

or via script tag:

<script src="https://cdn.jsdelivr.net/npm/event-emitter-object@4/dist/event-emitter-object.iife.js" crossorigin type="text/javascript"></script>

but there are lots of other options. See distribution report below.

Usage

Simple logger:

const {create} = require('event-emitter-object')

const logger = create()

logger.on('criticalError', function(err) {
  // send log to the server
})

// ... when an error happens:
logger.emit('criticalError', new Error('resourceNotFound'))

When arguments and return values matter:

const emailMessages = create()

emailMessages.on('emailMessage', function(recipient, subject, message) {
  // send an email and return the id of the sent message
  return {id: 1}
})

const results = emailMessages.emit('emailMessage', ['sample@example.com', 'Hey', 'Lorem ipsum.'])
// results == [{ok: 1}]

Return values are always array because multiple event functions can be attached to the same event:

const emailMessages = create()

emailMessages.on('emailMessage', function(recipient, subject, message) {
  // send an email and return the id of the sent message
  return {id: 1}
})

emailMessages.on('emailMessage', function(recipient, subject, message) {
  return 'ok'
})

const results = emailMessages.emit('emailMessage', ['sample@example.com', 'Hey', 'Lorem ipsum.'])
// results == [{ok: 1}, 'ok']

An event that will be invoked by the emitter just once:

const analytics = create()

analytics.on('view', function(id, title) {
  // save visitor and landing page info
  return 'done'
}, {once: true})

analytics.on('view', function(id, title) {
  // send page view to the analytics server
  return 'ok'
})

const results = analytics.emit('view', [1, 'Homepage'])
// results == ['done', 'ok']

const results2 = analytics.emit('view', [2, 'Contact'])
// results2 == ['ok']

Distributions Report

This is an auto-generated report that shows the type, name and size of the bundles available to use individually.

[
  "event-emitter-object.amd.js (1.08 KB)",
  "event-emitter-object.amd.polyfilled.js (10.61 KB)",
  "event-emitter-object.cjs.js (1.08 KB)",
  "event-emitter-object.cjs.polyfilled.js (10.64 KB)",
  "event-emitter-object.es.js (1.06 KB)",
  "event-emitter-object.es.polyfilled.js (10.63 KB)",
  "event-emitter-object.iife.js (1.10 KB)",
  "event-emitter-object.iife.polyfilled.js (10.63 KB)",
  "event-emitter-object.umd.js (1.30 KB)",
  "event-emitter-object.umd.polyfilled.js (10.82 KB)"
]

Babel Polyfills Report

This is an auto-generated report that shows the pollyfils added by core-js based on the targets configuration described below.

// polyfills:
[]
// based on the targets:
{
  "android": "4.4.3",
  "chrome": "49",
  "edge": "18",
  "firefox": "78",
  "ie": "10",
  "ios": "6",
  "opera": "73",
  "safari": "5.1",
  "samsung": "4"
}

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