Cache-Control

• MDN Cache-Control
• https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching
• https://support.cloudflare.com/hc/en-us/articles/115003206852-Understanding-Origin-Cache-Control
• max-age=0 vs no-cache
  • https://stackoverflow.com/a/1383359/1870054
• If-None-Match
  • W/ weak validator
  • GET, HEAD
  • 值为 etag, 存在则返回 304 Not Modified
  • 修改操作, 412 Precondition Failed
  • If-None-Match: "<etag>"[, "<etag>"]

请求

Cache-Control: max-age=<seconds>
Cache-Control: max-stale[=<seconds>]
Cache-Control: min-fresh=<seconds>
Cache-Control: no-cache
Cache-Control: no-store
Cache-Control: no-transform
Cache-Control: only-if-cached

响应

Cache-Control: must-revalidate
Cache-Control: no-cache
Cache-Control: no-store
Cache-Control: no-transform
Cache-Control: public
Cache-Control: private
Cache-Control: proxy-revalidate
Cache-Control: max-age=<seconds>
Cache-Control: s-maxage=<seconds>

Cache-Control: immutable
Cache-Control: stale-while-revalidate=<seconds>
Cache-Control: stale-if-error=<seconds>

• private - 面向单用户 - Authorization - browser 缓存
• public - 多用户共享缓存 - proxy cache 缓存
• post-check
• pre-check
• immutable
  • max-age 内避免尝试校验缓存

# 单位为秒
Cache-Control: public, max-age=3600
Expires: Thu, 01 Dec 2014 16:00:00 GMT

• Cache-Control: public, max-age=86400
  • static asset
• Cache-Control: no-store
  • 不缓存
• Cache-Control: private, max-age=3600
  • 浏览器缓存但 Proxy 不缓存
• Cache-Control: public, no-cache
  • prefer revalidation when served
• Cache-Control: public, no-cache, proxy-revalidate or Cache-Control: public, s-maxage=0
  • Cache assets in proxy caches but REQUIRE revalidation by the proxy when served
• Cache-Control: public, no-cache, must-revalidate
  • Cache assets in proxy caches, but REQUIRE revalidation by any cache when served
• Cache-Control: public, no-transform
  • Cache assets, but ensure the proxy does not modify it
• Cache-Control: public, max-age=3600, stale-if-error=60
  • Cache assets with revalidation, but allow stale responses if origin server is unreachable
• Cache-Control: public, max-age=7200, s-maxage=3600
  • Cache assets for different amounts of time on Cloudflare and in visitor browsers
• Cache-Control: max-age=600, stale-while-revalidate=30
  • Cache an asset and serve while asset is being revalidated
• https://developers.cloudflare.com/cache/about/cache-control

平台

• x-vercel-cache
  • HIT, MISS
• x-vercel-id
• cf-cache-status
  • HIT, MISS, EXPIRED, DYNAMIC, BYPASS