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

$3

``javascript

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

$3

`javascript
// 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

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

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

$3

`javascript
// @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__ |