Post 13: HTTP Caching: Cache-Control, ETags & the Browser's Memory

[honeycoder96]

Epic: #15
Block: 7 — The Response Arrives
Series order: 13 of 18

Description

The complete HTTP caching model — from the directives that control it to the conditional request dance that saves bandwidth to the Service Worker layer that makes it programmable.

Key topics

• Cache-Control directives: max-age, no-cache, no-store, public, private, immutable
• Fresh vs stale: when the browser uses a cached response without asking the server
• Revalidation: ETag and Last-Modified — sending a conditional request
• 304 Not Modified: the server confirms the cached version is still valid — no body sent
• The Vary header: caching separate responses for different Accept-Encoding or Accept-Language values
• Cache busting: why asset filenames include content hashes (main.a3f2c1.js)
• Service Worker caching strategies: cache-first, network-first, stale-while-revalidate
• The full decision flow: what the browser checks and in what order before making a network request