1. A Service Worker is a script which runs in the web browsers and manages the caching for web applications. This script runs in the background and don’t need any user interactions.

They can query a local cache and deliver a cached response, if it is available in the cache. This makes your webapp more reliable and increase its performances.

Service Worker

2. A Service Worker is a programmable network proxy as it intercepts all outgoing HTTP requests and use by allowing you to control how network requests from your page are handled.

3. The Service Worker is a Javascript method that enables applications to take advantage of persistent data in the background processing, including hooks to enable bootstrapping of web applications while offline.

4. Service Worker scripts run on a separate thread in the browser from the pages they control. There are ways to communicate between workers and pages, but they execute in a separate scope.

5. Service workers are not meant to and do not have the ability to manipulate the DOM directly.

6.  Some history: the older form of browser caching, AppCache, was a more error-prone solution for offline-first ready applications. You can think of service workers as their successor.

7. The Service Worker activity is not solely for offline. User benefits from SW during moments of slow or lowered connectivity. Rather than waiting endless seconds for the page to load, a previous cache is presented initially. Because even high speed internet can be unpredictable, connectivity can drop intermittently throughout a session. Caching your site ensures there’s always a version ready to go despite the shortcomings of ISP or cell providers. it makes your webapp behave more smooth and user-friendly.