event-notifier

A minimal event system built on the Subscriber-Controlled Pattern,
which empowers listeners to handle their own cleanup automatically.

Install

npm install event-notifier

Or use directly via CDN:

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/index.global.js"></script>
<script>
  const notifier = new EventNotifier(); // Global name in UMD
</script>

Usage

import Notifier from 'event-notifier';

function listener(data) {
  console.log('Received:', data);
}

// Optional auto-cleanup: unregister after 5 seconds
listener.onSubscribe = (release) => {
  setTimeout(release, 5000);
};

const notifier = new Notifier();
notifier.addListener('userLogin', listener);

notifier.notify('userLogin', 'User logged in!');

API

addListener(event: string, listener: function): () => void

Adds a listener to an event.
If listener.onSubscribe exists, it's called with a release function.

removeListener(event: string, listener: function)

Manually removes a specific listener.

notify(event: string, ...args: any[])

Triggers all listeners for the given event.

Tutorial

How add listener call once time

import Notifier from 'event-notifier';

const notifier = new Notifier();

function listener(data) {
  console.log('Received:', data);
}

const wrapper = (data) => {
  notifier.removeListener('userLogin', wrapper);
  listener(data);
};

notifier.addListener('userLogin', wrapper);

notifier.notify('userLogin', 'User logged in!');
notifier.notify('userLogin', 'Will not be called again');

TypeScript

import type { Listener } from 'event-notifier';

Here is the type definition for reference only

type Listener = ((...args: any[]) => void) & {
  onSubscribe?: (release: () => void) => void;
};

License MIT © Khánh Nguyễn