Cache Headers

Bklar provides helpers on the context for setting standard HTTP caching headers — Cache-Control, ETag, and Last-Modified.

Cache-Control

Use ctx.cacheControl() to set directives:

app.get("/static", (ctx) => {
  ctx.cacheControl({
    public: true,
    maxAge: 3600,
    immutable: true,
  });
  return ctx.text("cached response");
});

Supported directives: public, private, maxAge, sMaxAge, noCache, noStore, noTransform, mustRevalidate, proxyRevalidate, mustUnderstand, immutable, staleWhileRevalidate, staleIfError.

ETag

Use ctx.etag() for conditional caching with If-None-Match:

app.get("/data", (ctx) => {
  const hash = computeHash(data);
  const notModified = ctx.etag(hash);
  if (notModified) return notModified; // 304
  return ctx.json(data);
});

Last-Modified

Use ctx.lastModified() for time-based conditional caching:

app.get("/feed", (ctx) => {
  const lastUpdate = new Date("2024-01-15");
  const notModified = ctx.lastModified(lastUpdate);
  if (notModified) return notModified; // 304
  return ctx.json(feed);
});

Both methods automatically check the incoming If-None-Match / If-Modified-Since headers and return 304 Not Modified when appropriate.