Donation Alerts - Events

A client that makes it very straightforward to listen to various Donation Alerts events.

Installation

Using npm:

npm i @donation-alerts/events @donation-alerts/api

Using yarn:

yarn add @donation-alerts/events @donation-alerts/api

Usage

You have 2 options to listen to events:

1. UserEventsClient - Single-user client.
2. EventsClient - Multiple-user client. This client internally creates a UserEventsClient instance for each user you add.

First of all, in order to be able to listen to Donation Alerts events, you must create an ApiClient instance. Check the documentation page to read more.

Creating a single-user client

To instantiate a UserEventsClient, you must provide UserEventsClientConfig to the UserEventsClient constructor.

import { ApiClient } from '@donation-alerts/api';
import { UserEventsClient } from '@donation-alerts/events';

const userId = 123456789;
const apiClient = new ApiClient({
	//...
});

const userEventsClient = new UserEventsClient({
	user: userId,
	apiClient: apiClient
});

Listening to events

After creating a UserEventsClient instance, you can now listen to events of your choice.

import {
	DonationAlertsDonationEvent,
	DonationAlertsGoalUpdateEvent,
	DonationAlertsPollUpdateEvent
} from '@donation-alerts/events';

const donationsListener = userEventsClient.onDonation((evt: DonationAlertsDonationEvent) => {
	// Handle the event...
});

const goalUpdatesListener = userEventsClient.onGoalUpdate((evt: DonationAlertsGoalUpdateEvent) => {
	// Handle the event...
});

const pollUpdatesListener = userEventsClient.onPollUpdate((evt: DonationAlertsPollUpdateEvent) => {
	// Handle the event...
});

It's that simple! These methods return an EventsListener instance.

Check the documentation pages of the event objects to explore all data you can use: DonationAlertsDonationEvent, DonationAlertsGoalUpdateEvent, DonationAlertsPollUpdateEvent

If you no longer need any listeners, you can remove them by calling remove method of the EventsListener instance.

await donationsListener.remove();

Or using removeEventsListener method of the UserEventsClient instance:

await userEventsClient.removeEventsListener(donationsListener);

[!IMPORTANT] The user you want to set up listeners for must be added to the AuthProvider that you passed to the ApiClient instance. The access token of the user also must have the required scopes to successfully subscribe to the private channels.

Connection

The client automatically establishes a connection to the Donation Alerts Centrifugo server when you create any listener, as described above. If you remove all listeners, the connection will be automatically closed.

You can also manually manage the connection state by using connect, disconnect, or reconnect methods of the UserEventsClient instance.

disconnect

disconnect method closes the connection. The client will not attempt to reconnect after manually calling disconnect method. This method also accepts the optional boolean removeListeners argument. If you pass true, the client will remove all listeners. By default, it is set to false, so the client will store listeners and will be able to restore them on the next manual connection.

await userEventsClient.disconnect(true);

connect

connect method establishes a connection to a Donation Alerts Centrifugo server. This method accepts an optional boolean argument restoreExistingListeners. If you call disconnect method without removing listeners (the default behavior), the client will be able to restore all listeners. By default, this is set to true.

await userEventsClient.connect(true);

reconnect

reconnect internally calls disconnect method, followed by calling connect method. You can pass the optional boolean removeListeners argument to remove all existing listeners. By default, this is set to false, so the client will restore all listeners after reconnection.

The client establishes a persistent connection, so in most cases, it handles disconnections (such as network problems) and attempts to reconnect with exponential backoff (the first attempt performs immediately, and the maximum interval between attempts is 30 seconds).

If you want to have full control over the connection flow, you can listen to onConnect and onDisconnect events:

userEventsClient.onConnect(() => {
	console.log('CONNECTED');
});

userEventsClient.onDisconnect((reason: string, reconnect: boolean) => {
	console.log('DISCONNECTED', reason, reconnect);
});

The reconnect parameter of the onDisconnect callback indicates whether the client will attempt to reconnect to the server. Handle it according to your needs.

Creating a multiple-user client

If you need to listen to events of multiple users, consider using EventsClient. To create an EventsClient instance, you must provide ApiClient through EventsClientConfig.

import { ApiClient } from '@donation-alerts/api';
import { EventsClient } from '@donation-alerts/events';

const apiClient = new ApiClient({
	//...
});

const eventsClient = new EventsClient({
	apiClient: apiClient
});

Managing users

After creating an EventsClient instance, you should register users to be able to listen to events.

addUser

Adds a user to the client. If the user already exists, an error will be thrown.

import { UserEventsClient } from '@donation-alerts/events';

const userId = 123456789;
const userEventsClient: UserEventsClient = eventsClient.addUser(userId);

Returns a UserEventsClient instance.

hasUser

Checks whether a user was added to the client.

const userId = 123456789;
const hasUser: boolean = eventsClient.hasUser(userId);

Returns boolean.

removeUser

The client will be unsubscribed from all user channels, and the connection will be closed before actually removing the user from the client.

Does nothing if user is not added to the client.

const userId = 123456789;
eventsClient.removeUser(userId);

getUserClient

You can get the UserEventsClientConfig of the user by using getUserClient method.

const userId = 123456789;
const userEventsClient = eventsClient.getUserClient(userId);

Listening to events

Creating event listeners is almost the same as for UserEventsClient, but you also need to provide the ID of the user you want to listen to events from.

import {
	DonationAlertsDonationEvent,
	DonationAlertsGoalUpdateEvent,
	DonationAlertsPollUpdateEvent
} from '@donation-alerts/events';

const userId = 123456789;

const donationsListener = eventsClient.onDonation(userId, (evt: DonationAlertsDonationEvent) => {
	console.log(evt);
});

const goalUpdatesListener = eventsClient.onGoalUpdate(userId, (evt: DonationAlertsGoalUpdateEvent) => {
	console.log(evt);
});

const pollUpdatesListener = eventsClient.onPollUpdate(userId, (evt: DonationAlertsPollUpdateEvent) => {
	console.log(evt);
});

These methods return an EventsListener instance. You can remove these listeners by calling remove method. If you remove all listeners for a single user, the connection for this user will be closed. The user's client won't be removed from the EventsClient instance, so you will be able to restore the connection at any time.

EventsClient also allows you to listen to connection events:

eventsClient.onConnect((userId: number) => {
	console.log(`[${userId}] CONNECTED`);
});

eventsClient.onDisconnect((userId: number, reason: string, reconnect: boolean) => {
	console.log(`[${userId}] DISCONNECTED`, reason, reconnect);
});

For more information check the documentation.