publisher-subscriber-pattern

About

• Javascript implementation of publisher subscriber pattern
• Can be used with different event emitters including browser window
• Provides Publisher class

Installation

npm i publisher-subscriber-pattern

Example

The example uses the browser's window object as emitterInstance. Other valid emitter instances can be also used.

import { Publisher } from 'publisher-subscriber-pattern';

const publisher = new Publisher(window, window.addEventListener, window.removeEventListener);

Publisher subscribe method returns function, which can be used later to unsubscribe from the event.

const unsubscribe = publisher.subscribe('scroll', (event) => {});

// ...foo code...

unsubscribe();

API

Publisher

• Parameters: emitterInstance, addListener, removeListener
• Methods: subscribe, unsubscribeAll, eventSubscribersCount, subscribersCount

Parameters

emitterInstance

• Object that will be bound to addListener and removeListener as this (see Function.prototype.bind)

addListener, removeListener

• Methods exposed by emitterInstance which add and remove event listeners, respectively

Methods

subscribe

• Required parameters: eventName, eventCallback
• Optional parameter: subscriberInstance that will be bound to eventCallback as this
• Subscribes eventCallback to eventName, so whenever event occurs the eventCallback is called (with subscriberInstance as this, if provided)
• Returns unsubscribe function

unsubscribeAll

• Unsubscribes all eventCallbacks from all eventNames
• Runs removeListener of emitterInstance fro all eventNames

eventSubscriberCount

• Required parameter: eventName
• Returns number of eventCallbacks subscribed to the evenName

subscribersCount

• Returns number of eventCallbacks subscribed to all evenNames

Dependencies

Production dependencies

• Package has no production dependencies

Main development dependencies

• Typescript
• Jasmine, chai, sinon
• Babel
• Node (EventEmitter)