RxPubSub

1. Description
2. Installation
3. Usage
4. Methods
5. Git repository
6. Version

1. Description

rx-pubsub or RxPubSub is a "Publish and Subscribe" service based on RxJs ReplaySubject.

2. Installation

Install the module into your application and save it as a dev dependency in your package.json file

npm install rx-pubsub --save-dev

3. Usage

In order to use the RxPubSub service you have to include/import it into your application:

import {RxPubSub} from "rx-pubsub";

If you want to use it in a plain/vanilla Javascript project then you might just include the js file into your html/page application:

<script type="application/javascript" src="./node_modules/rx-pubsub/dist/rx-pubsub.min.js"></script>

Create new RxPubSub object and use it.

Example

let eventName = 'testEvent';
  
console.log('register 1st subscriber to the event');
let sub1 = RxPubSub.subscribe(eventName, (data) => {
    console.log('1st subscriber receives data: ', data);
});  
console.log('register 2nd subscriber to the same event');
let sub2 = RxPubSub.subscribe(eventName, (data) => {
    console.log('2nd subscriber receives data: ', data);
});
  
console.log('publish data to the event');
RxPubSub.publish(eventName, {testProp: 'test Value'});
  
console.log('register 3rd subscriber to the same event');
let sub3 = RxPubSub.subscribe(eventName, (data) => {
    console.log('3rd subscriber receives data: ', data);
});

Output

register 1st subscriber to the event
register 2nd subscriber to the same event
publish data to the event
  
1st subscriber receives data: 
Object {testProp: "test Value"}
  
2nd subscriber receives data: 
Object {testProp: "test Value"}
  
register 3rd subscriber to the same event
  
3rd subscriber receives data:
Object {testProp: "test Value"}

4. Methods

publish(eventName: string, data: any, previousMessagesNr: number = 1)

Publish data to an event

Parameters:
eventName - Event which should be fired
data - Data sent to all Subscribers of the event
previousMessagesNr - Maximum element count of the replay buffer

Return:
Method returns void.

subscribe(eventName: string, callback: (data?: any) => any, previousMessagesNr: number = 1)

Register a new subscriber/callback to an event

Parameters:
eventName - Event to subscribe to
callback - Callback to be called when the eventName is fired
previousMessagesNr - Maximum element count of the replay buffer

Return:
Method returns Subscription if callback and eventName is provided. FALSE if there is an error.

subscribeOnce(eventName: string, callback: (data?: any) => any)

Subscribe to an event only one single time.
After the first publish the Subscriber will be destroyed and will not receive any further data published to its eventName.

Parameters:
eventName - Event to subscribe to
callback - Callback to be called when the eventName is fired
previousMessagesNr - Maximum element count of the replay buffer

Return:
Method returns Subscription if callback and eventName is provided. FALSE if there is an error.

unsubscribe(subscriber: Subscription)

Unsubscribe a Subscriber from the event.

Parameters:
subscriber - the Subscriber which should be destroyed/unsubscribed

Return:
Method returns void.

As the subscribe() and subscribeOnce() methods returns back the RxJs/Subscription object you can use its available methods. The most important thing is the unsubscribe() method provided directly by the RxJs/Subscription.
Hence, if you have the Subscription object:

let eventName = 'testEvent';
  
let subscription = RxPubSub.subscribe(eventName, (data) => {
    console.log('received data: ', data);
});  

you can unsubscribe it using the RxPubSub method:

RxPubSub.unsubscribe(subscription);

or using the rxjs/Subscription method:

subscription.unsubscribe();

unsubscribeAll(subscribers: Subscription[])

Unsubscribe a list of Subscribers from the event

Parameters:
subscribers - The list of subscribers which should be destroyed/unsubscribed

Return:
Method returns void.

dispose(eventName: string)

Unsubscribe all observers from the event and release resources.

Parameters:
eventName - event which should be destroyed.

Return:
Method returns void.

hasSubscribers(eventName: string)

Check if a Subject attached to the event eventName has Subscribers.

Parameters:
eventName - Name of the event to be checked if it has Subscribers.

Return:
Method returns boolean:
true - if there is at least one Subscriber
false - if there are no Subscribers at all

getEvents()

Retrieve the entire list of the events and the Subjects attached to them.

Return:
Method returns an Object which contains the list of the events and the Subjects attached to them.

getSubjects()

An alias for the getEvents() method.

Return:
Method returns an Object which contains the list of the events and the Subjects attached to them.

5. Git repository

https://github.com/t0w5a/rx-pubsub

6. Version

0.2.1