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eventemitter3

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eventemitter3

EventEmitter3 focuses on performance while maintaining a Node.js AND browser compatible interface.

    5.0.0latest

Version published
Maintainers
3
Weekly downloads
23,776,315
increased by5.52%

Weekly downloads

Changelog

Source

Breaking changes

  • The umd directory has been renamed to dist and the eventemitter3.min.js bundle to eventemitter3.umd.min.js (#252).
  • Importing the module with the TypeScript-specific import EventEmitter = require('eventemitter3') syntax is no longer supported (#252).

Features

  • Added ESM support (#252).

Readme

Source

EventEmitter3

Version npmBuild StatusCoverage StatusIRC channel

Sauce Test Status

EventEmitter3 is a high performance EventEmitter. It has been micro-optimized for various of code paths making this, one of, if not the fastest EventEmitter available for Node.js and browsers. The module is API compatible with the EventEmitter that ships by default with Node.js but there are some slight differences:

  • Domain support has been removed.
  • We do not throw an error when you emit an error event and nobody is listening.
  • The newListener and removeListener events have been removed as they are useful only in some uncommon use-cases.
  • The setMaxListeners, getMaxListeners, prependListener and prependOnceListener methods are not available.
  • Support for custom context for events so there is no need to use fn.bind.
  • The removeListener method removes all matching listeners, not only the first.

It's a drop in replacement for existing EventEmitters, but just faster. Free performance, who wouldn't want that? The EventEmitter is written in EcmaScript 3 so it will work in the oldest browsers and node versions that you need to support.

Installation

$ npm install --save eventemitter3

CDN

Recommended CDN:

https://unpkg.com/[email protected]/umd/eventemitter3.min.js

Usage

After installation the only thing you need to do is require the module:

var EventEmitter = require('eventemitter3');

And you're ready to create your own EventEmitter instances. For the API documentation, please follow the official Node.js documentation:

http://nodejs.org/api/events.html

Contextual emits

We've upgraded the API of the EventEmitter.on, EventEmitter.once and EventEmitter.removeListener to accept an extra argument which is the context or this value that should be set for the emitted events. This means you no longer have the overhead of an event that required fn.bind in order to get a custom this value.

var EE = new EventEmitter() , context = { foo: 'bar' }; function emitted() { console.log(this === context); // true } EE.once('event-name', emitted, context); EE.on('another-event', emitted, context); EE.removeListener('another-event', emitted, context);

Tests and benchmarks

This module is well tested. You can run:

  • npm test to run the tests under Node.js.
  • npm run test-browser to run the tests in real browsers via Sauce Labs.

We also have a set of benchmarks to compare EventEmitter3 with some available alternatives. To run the benchmarks run npm run benchmark.

Tests and benchmarks are not included in the npm package. If you want to play with them you have to clone the GitHub repository. Note that you will have to run an additional npm i in the benchmarks folder before npm run benchmark.

License

MIT

Keywords

FAQs

What is eventemitter3?

EventEmitter3 focuses on performance while maintaining a Node.js AND browser compatible interface.

Is eventemitter3 popular?

The npm package eventemitter3 receives a total of 19,983,449 weekly downloads. As such, eventemitter3 popularity was classified as popular.

Is eventemitter3 well maintained?

We found that eventemitter3 demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago.It has 3 open source maintainers collaborating on the project.

Last updated on 28 Nov 2022

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