Service workers act as programmable network proxies that sit between a web page and the internet, enabling offline support, background sync and resource caching.

Registering the Worker

First step is to check browser support and register the script.

• Wrap registration in a load event listener
• Use navigator.serviceWorker.register with the script path
• Provide feedback on success or error
• Log current lifecycle stage for debugging

Installation and Caching

During install the worker creates a cache and stores essential files.

• Define a constant cache name
• List URLs to pre‑cache
• Call event.waitUntil with caches.open and cache.addAll
• Confirm cache opening with console message

Activation and Cache Cleanup

Activation removes outdated caches to keep storage tidy.

• Listen for the activate event
• Iterate existing cache names
• Delete any name that does not match the current version
• Use Promise.all to ensure completion before control passes

Fetch Interception and Offline Support

Fetch handler serves cached responses or falls back to network.

• Match incoming request against cache
• Return cached response when found
• Otherwise perform a network fetch
• Optionally add fallback page for failed network

Deploying on Vultr with Nginx and Let’s Encrypt

Set up a Linux instance, configure Nginx as a reverse proxy, and obtain TLS certificates.

• Create a systemd service that runs the Python HTTP server
• Point Nginx to the service’s localhost port
• Run Certbot to issue a certificate for your domain
• Reload Nginx to apply HTTPS settings
• Test service worker registration over a secure origin

For a deeper look at HTTPS setup on Vultr see related deployment guide. Review privacy considerations in GPC standards draft. The service worker runs in the background separate from the page thread.