event-target-shim

What is event-target-shim?

The event-target-shim npm package provides a cross-platform, shim implementation of the EventTarget interface, allowing developers to use a consistent API for event handling across different environments. It supports the standard addEventListener, removeEventListener, and dispatchEvent methods, along with custom event types. This makes it useful for projects that need to handle events in both browser and non-browser environments, such as Node.js applications or web components.

What are event-target-shim's main functionalities?

Basic Event Handling

This demonstrates how to create an instance of EventTarget, add an event listener for a custom event type, and then dispatch an event of that type. It's the basic usage for handling custom events.

const EventTargetShim = require('event-target-shim');
const myEventTarget = new EventTargetShim();

myEventTarget.addEventListener('customEvent', function(event) {
  console.log(`Received: ${event.type}`);
});

myEventTarget.dispatchEvent(new EventTargetShim.Event('customEvent'));

Using Options for addEventListener

This example shows how to use the `once` option with `addEventListener` to automatically remove the event listener after it has been invoked once, demonstrating the package's support for event listener options.

const EventTargetShim = require('event-target-shim');
const myEventTarget = new EventTargetShim();

myEventTarget.addEventListener('customEvent', function(event) {
  console.log(`Received: ${event.type}`);
}, { once: true });

myEventTarget.dispatchEvent(new EventTargetShim.Event('customEvent'));
myEventTarget.dispatchEvent(new EventTargetShim.Event('customEvent'));

Other packages similar to event-target-shim

eventemitter3

EventEmitter3 is a high-performance event emitter. While event-target-shim mimics the EventTarget interface specifically, EventEmitter3 provides a more general-purpose event handling mechanism. It doesn't follow the browser's EventTarget API as closely but offers a lightweight, fast solution for event management.

wolfy87-eventemitter

Wolfy87's EventEmitter is another alternative for event handling, offering a similar set of functionalities to event-target-shim but with a different API. It provides a more object-oriented approach to event handling, with features like namespaced events, which can be particularly useful in complex applications. Compared to event-target-shim, it might offer more flexibility in certain scenarios but doesn't aim to replicate the EventTarget interface directly.

README

event-target-shim

An implementation of WHATWG EventTarget interface and WHATWG Event interface. This implementation supports constructor, passive, once, and signal.

This implementation is designed ...

• Working fine on both browsers and Node.js.
• TypeScript friendly.

💿 Installation

Use npm or a compatible tool.

npm install event-target-shim

📖 Getting started

import { EventTarget, Event } from "event-target-shim";

// constructor (was added to the standard on 8 Jul 2017)
const myNode = new EventTarget();

// passive flag (was added to the standard on 6 Jan 2016)
myNode.addEventListener(
  "hello",
  (e) => {
    e.preventDefault(); // ignored and print warning on console.
  },
  { passive: true }
);

// once flag (was added to the standard on 15 Apr 2016)
myNode.addEventListener("hello", listener, { once: true });
myNode.dispatchEvent(new Event("hello")); // remove the listener after call.

// signal (was added to the standard on 4 Dec 2020)
const ac = new AbortController();
myNode.addEventListener("hello", listener, { signal: ac.signal });
ac.abort(); // remove the listener.

• For browsers, use a bundler such as Webpack to bundle.
  • If you want to support IE11, use import {} from "event-target-shim/es5" instead. It's a transpiled code by babel. It depends on @baebl/runtime (^7.12.0) package.
• The AbortController class was added to the standard on 14 Jul 2017. If you want the shim of that, use abort-controller package.

📚 API Reference

See docs/reference.md.

💥 Migrating to v6

See docs/migrating-to-v6.md.

📰 Changelog

See GitHub releases.

🍻 Contributing

Contributing is welcome ❤️

Please use GitHub issues/PRs.

Development tools

• npm install installs dependencies for development.
• npm test runs tests and measures code coverage.
• npm run watch:mocha runs tests on each file change.