publisher-subscriber-pattern
v2.0.4
Published
Publisher subscriber pattern that can be used with different event emitters including browser window
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About
- Javascript implementation of publisher subscriber pattern
- Can be used with various event emitters including browser's window object
- 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, 'addEventListener','removeEventListener');
Publisher's subscribe method returns function, which can be used later to unsubscribe from the publisher's event.
const unsubscribe = publisher.subscribe('scroll', (event) => {});
// ...foo code...
unsubscribe();
There is also a method unsubscribeAll for unsubscribing all subscribers from all emitter's events.
publisher.unsubscribeAll();
API
Publisher
- Parameters: emitterInstance, addListenerMethodName, removeListenerMethodName
- Methods: subscribe, unsubscribeAll, eventSubscribersCount, subscribersCount
Parameters
emitterInstance
- Object, which exposes addListener and removeListener methods
- Behind the scenes, the emitterInstance is bound to addListener and removeListener methods as this (see Function.prototype.bind)
addListenerMethodName, removeListenerMethodName
- Names of methods (strings), which are exposed by emitterInstance and, which add and remove event listeners, respectively
Methods
subscribe
Required parameters: eventName, eventCallback
Optional parameter: subscriberInstance, which will be bound to the eventCallback argument as this (see Function.prototype.bind)
Method subscribes eventCallback to eventName, so whenever event occurs the eventCallback is called
Returns function for unsubscribing from the event
unsubscribeAll
- Unsubscribes all publisher's eventCallbacks from all emitter's eventNames
eventSubscriberCount
- Required parameter: eventName
- Returns number of subscribers' eventCallbacks subscribed to publisher's eventName
subscribersCount
- Returns number of subscriber's eventCallbacks subscribed to all publisher's eventNames
Dependencies
Production dependencies
- Package has no production dependencies
Main development dependencies
- Typescript
- Jasmine, chai, sinon
- Babel
- Node (EventEmitter)