Service Worker

Definitions

1. A JavaScript proxy that runs in the background between your web app and the network. Intercepts fetch requests, enabling offline support, caching strategies (cache-first, network-first, stale-while-revalidate), push notifications, and background sync. The technology that makes Progressive Web Apps possible.

   In plain English: A background script in your browser that intercepts network requests, enabling offline support and smart caching.

   Example: "The service worker caches the app shell on first visit — subsequent loads work offline and feel instant."

Related Terms

• service worker
• DOM
• Inspector
• Offline-First
• WebRTC
• Web Worker
• Intersection Observer
• IndexedDB
• Shadow DOM
• Web Push
• WebGL