Push Notifications

Why Push Notifications?

The Push API + Notifications API

Requesting Permission

async function enableNotifications() {
  const permission = await Notification.requestPermission();
  if (permission !== 'granted') {
    alert('Notifications denied');
    return;
  }
  // proceed to subscribe...
}

Push Subscription

async function subscribeToPush() {
  const reg = await navigator.serviceWorker.ready;
  const sub = await reg.pushManager.subscribe({
    userVisibleOnly: true, // required: every push must show a notification
    applicationServerKey: urlBase64ToUint8Array(VAPID_PUBLIC_KEY)
  });
  // Send sub to your server:
  await fetch('/api/save-subscription', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(sub)
  });
}

VAPID Keys

# Generate VAPID keys with web-push CLI:
npx web-push generate-vapid-keys

# Output:
# Public Key: BJ...
# Private Key: ka...

Server-Side Push

import webpush from 'web-push';

webpush.setVapidDetails(
  'mailto:you@example.com',
  process.env.VAPID_PUBLIC,
  process.env.VAPID_PRIVATE
);

await webpush.sendNotification(savedSubscription, JSON.stringify({
  title: 'New message',
  body: 'Alice sent you a message',
  url: '/inbox/123'
}));

Handling Push in the Service Worker

// sw.js
self.addEventListener('push', (event) => {
  const data = event.data ? event.data.json() : {};
  event.waitUntil(
    self.registration.showNotification(data.title || 'Notification', {
      body: data.body,
      icon: '/icons/192.png',
      badge: '/icons/badge.png',
      data: { url: data.url }
    })
  );
});

Notification Click Handler

self.addEventListener('notificationclick', (event) => {
  event.notification.close();
  const url = event.notification.data.url || '/';
  event.waitUntil(
    clients.matchAll({ type: 'window' }).then(clientList => {
      for (const client of clientList) {
        if (client.url.endsWith(url) && 'focus' in client) return client.focus();
      }
      return clients.openWindow(url);
    })
  );
});

Notification Options

self.registration.showNotification('Message', {
  body: 'Alice sent you a photo',
  icon: '/icons/192.png',
  image: '/images/alice-photo.jpg',
  actions: [
    { action: 'view', title: 'View' },
    { action: 'reply', title: 'Reply' }
  ],
  tag: 'message-from-alice', // replaces earlier 'message-from-alice'
  requireInteraction: false
});

Unsubscribing

async function disablePush() {
  const reg = await navigator.serviceWorker.ready;
  const sub = await reg.pushManager.getSubscription();
  if (sub) {
    await sub.unsubscribe();
    await fetch('/api/delete-subscription', {
      method: 'POST',
      body: JSON.stringify({ endpoint: sub.endpoint })
    });
  }
}

iOS Support

Best Practices

Common Pitfalls

Quick Check

Recap: Push Notifications