technical

Service worker

Browser background script for caching/offline.

Definition

A service worker is a JavaScript file that runs in the background, separate from the page. Powers offline support, push notifications, and advanced caching strategies. Foundation of PWAs.

Related terms

Core Web Vitals

Google's user experience metrics.

LCP

Largest contentful paint — page load metric.

CLS

Cumulative layout shift — visual stability metric.

INP

Interaction to next paint — responsiveness metric.

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