DKX/EventDispatcher

Event dispatcher for node.js

Installation

Dependencies:

• reflect-metadata

with npm:

$ npm install --save @dkx/event-dispatcher

or with yarn:

$ yarn add @dkx/event-dispatcher

Events

Events should be small value object classes implementing the Event interface.

import {Event} from '@dkx/event-dispatcher';

class UserUpdatedEvent implements Event
{
    constructor(
        public readonly user: User,
        public readonly changes: any,
    ) {}
}

Subscribers

Subscribers are classes which contains subscriptions to defined events. They should implement the Subscriber interface.

import {Subscriber, Subscribe} from '@dkx/event-dispatcher';
import {UserUpdatedEvent} from './user-updated-event';

class UserUpdatedEmailNotification implements Subscriber
{
    @Subscribe()
    public onUserUpdated(event: UserUpdatedEvent): void
    {
        console.log(event);
        // todo send email
    }
}

Event to which the subscriber should subscribe is taken from method argument type (event: UserUpdatedEvent).

Subscription method can be also async and return Promise.

Call event

import {EventDispatcher} from '@dkx/event-dispatcher';
import {UserUpdatedEvent} from './user-updated-event';
import {UserUpdatedEmailNotification} from './user-updated-email-notification';

// create and register first subscriber
const events = new EventDispatcher;
events.addSubscriber(new UserUpdatedEmailNotification);

// dispatch event
events.dispatch(new UserUpdatedEvent(user, {}));