Web Notifier

web-notifier is a an backend library for abstracting push notification logic in Node.

We take care of the hard stuff:

• Sending notifications
• Managing push subscriptions
• Notification scheduling

The goal of this library is to abstract away the notification queue and validation logic and allow you to focus on your business logic.

Getting Started

Follow these steps to get the server logic setup quickly.

1. Install the dependency

   npm i -S web-notifier

2. Before we continue, you'll need to generate valid VAPID keys (if you haven't already) and store them for future use.

   npx web-push generate-vapid-keys

   There are two VAPID keys:

   • private key which should not be publicly accessible.
   • public key which can referenced in your frontend code.

   We recommend using a tool like dotenv to manage both public and private keys.

3. Instantiate an instance on the server

import WebNotifier, { InMemoryAdapter } "web-notifier";

const notifier = new WebNotifier({
  vapidKeys: {
    publicKey: process.env.VAPID_PUBLIC_KEY,
    privateKey: process.env.VAPID_PRIVATE_KEY,
    email: process.env.VAPID_EMAIL,
  },
  notificationDefaults: {
    badge: "/notification-badge.png",
    icon: "/android-chrome-192x192.png",
    url: "/",
  },
  getUserPushSubscriptions,
  removeUserPushSubscriptions,
  adapter: new InMemoryAdapter(),
});

4. Send a push notification

notifier.send(userId, {
  title: "This will send immediately",
});

You can also defer the message till a later date by using

const when = new Date();
when.setHours(when.getHours() + 1);
notifier.schedule(when, userId, {
  title: "This will send in 1 hour",
});

Adapters

WebNotifier needs to store information somewhere. The following information needs to be stored:

• Notification Queue - When you call notifier.schedule or notifier.send we store the notification and payload. We then periodically crawl storage for notifications that are ready to be sent.

The following adapters are available:

• InMemory - DO NOT USE THIS IN PRODUCTION - It's used to quickly scaffold and test, but the storage mechanism should be resilient to server restarts.

• MongoDb - This leverages MongoDB and mongoose as a storage mechanism

• CoreAdapter - If you need to implement your own storage mechanism for another service, the implementation should extend from CoreAdapter. InMemory adapter will be a good reference of how to properly construct an adapter.

Managing User Subscriptions

One thing this package does not do is user subscription management. From the client, you will receive a push subscription address. You'll need to store this and associate it with a user.

WebNotifier expects the following functions passed in:

• getUserPushSubscriptions - this function will provide a userId and it should return an array of push subscriptions to send to. You can provide one or a million, it will slowly send them as the resources are available.
• removeUserPushSubscriptions - Sometimes, users will block your push notifications. This function will allow you to remove a push subscription from a user.