publisher-subscriber-ts

Publisher subscriber library for javascript.

Setup

1. npm install
2. npm run prepare

Prepare will build this project and create a lib folder which'll contain publisher.min.js for consumption. It'll also create a ES6 version called publisher.es.js and couple of declaration files.

Running test

3. npm run test

This will execute Jest on project.

Usage

• This package has concept of Publisher and Subscriber

• A Publisher communicates with all it's Subscriber through something called Topic

• A Publisher can create any number of Topic and emit event/data to each Topic

• A Subscriber can subscribe/listen to any number of Topic by providing a callback function

• A Subscriber can unsubscribe any Topic at any given time

Example

1. Creating a Topic

// @class Publisher has static helper methods
const  topic1  =  Publisher.createTopic("Topic 1");

2. Subscribing a Topic

// Subscription option takes topic name and optional 'getLastValue' flag which indicates if subscriber should reveice last emitted value from topic
const  subscriptionOption  = {
	topicName: "Topic 1",
	getLastValue: true
};

// @class Publisher has static helper methods
const  subscription1  =  Publisher.subscribeTopic(subscriptionOption, (event) => {
	console.log('Callback function event: ', event);
});

3. Emitting date from topic

const  event  = {
	data: 'Some random data to be broadcasted'
};

// We use object created from "Publisher.createTopic()"
topic1.publish(event);

4. Unsubscribing a Topic

// @class Publisher has static helper methods. Pass subscription object to be unsubscribed.
Publisher.unsubscribeTopic(subscription1);

Documentation

1. @class Publisher

| Method | Description | | -------| ------------| |createTopic(topicName: string) | Creates new topic for given topic name| |subscribeTopic(option: SubscribeOption, callback: Function): Subscriber | Subscribe to a particular topic by providing option and a callback function| |unsubscribeTopic(subscriber: Subscriber) | Unsubscribe any given subscriber|

2. @class Subscriber

| Method | Description | |------- | ------------| |callBack | Getter for returning callback function| |id | Getter for returning subscrber ID| |topicName | Getter for returning topic name|

3. @class Topic

|Method | Description| |-------| -----------| |publish(event: any) | Publish any event for current topic. Once event is published all active subscribers will get a notification in callback function| |unsubscribe(subscription: Subscriber) | Method to unsubscribe/remove a listener of this topic| |topicName | Getter for returning topic name|

4. @interface SubscribeOption

|Property | Description| |-------- | -----------| |topicName | Required string option to pass name| |getLastValue | Optional boolean flag to indicate if last emitted value from topic should be re-emitted for given subscriber only. Default value is false |