Pubsub-distinct NPM

PubSubDistinct

1. Description

pubsub-distinct or PubSubDistinct is an extension of the rx-pubsub service. Additionally to the functionality of the rx-pubsub it has one more public method publishDistinct() which publishes only distinct data. It means, the same data will not be published on the same event twice in a row.

Example:

let eventName = 'testEvent';
  
console.log('register the subscriber to the event');
let sub1 = PubSubDistinct.subscribe(eventName, (data) => {
    console.log('subscriber receives data: ', data);
});  
  
console.log('publish data to the event');
PubSubDistinct.publishDistinct(eventName, {testProp: 'test Value'});

console.log('publish other data to the event');
PubSubDistinct.publishDistinct(eventName, {testProp: 'test Value 2'});

console.log('publish the same data as the previous one. the subscriber shouldn\'t be triggered!');
PubSubDistinct.publishDistinct(eventName, {testProp: 'test Value 2'});

console.log('publish new data');
PubSubDistinct.publishDistinct(eventName, {testProp: 'test Value 3'});

Output:

register the subscriber to the event  
  
publish data to the event  
subscriber receives data:  Object {testProp: "test Value"}  
  
publish other data to the event  
subscriber receives data:  Object {testProp: "test Value 2"}  
  
publish the same data as the previous one. the subscriber shouldn't be triggered!  
  
publish new data  
subscriber receives data:  Object {testProp: "test Value 3"}

This module is separated from the rx-pubsub because of its dependencies and the final size of the module. It is using object-hash module to generate the hash of the published data. As the result its size is 7 times bigger than rx-pubsub. So, if you don't need this feature, to publish only distinct data, please take a look at the module rx-pubsub.

2. Installation

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

npm install pubsub-distinct --save-dev

3. Usage

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

import {PubSubDistinct} from "pubsub-distinct";

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/pubsub-distinct/dist/pubsub-distinct.min.js"></script>

Create new PubSubDistinct object and use it as it's shown in the above example.

4. Methods

The only difference of this module from the rx-pubsub is the method publishDistinct():

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

Publish only distinct data to an event. The same data will not be published two times in a row!

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.

The description of other methods can be found in the rx-pubsub documentation.