Send messages when you're back online with Service Workers and Background Sync

This example of using background sync looks like it’s specific to Twilio, but the breakdown of steps is broad enough to apply to many situations:

On the page we need to:

1. Register a Service Worker
2. Intercept the “submit” event for our message form
3. Place the message details into IndexedDB, an in browser database
4. Register the Service Worker to receive a “sync” event

Then, in the Service Worker we need to:

1. Listen for sync events
2. When a sync event is received, retrieve the messages from IndexedDB
3. For each message, send a request to our server to send the message
4. If the message is sent successfully, then remove the message from IndexedDB

And that’s it.