early-hints

A library that uses Deno’s flash server (experimental) to serve 103 Early Hints.

Note: See here for 103 Early Hints.

import { contentType } from "https://deno.land/std@0.155.0/media_types/mod.ts";
import {
  earlyHintsResponse,
  withEarlyHints,
} from "https://deno.land/x/103_early_hints@$VERSION/unstable.ts";

Deno.serve(withEarlyHints(async function* (_request) {
  // sends early hints response
  yield earlyHintsResponse(["/style.css"]);

  // do some long task
  await new Promise((resolve) => setTimeout(resolve, 1000));

  // Please return the actual response at the end.
  return new Response("<!DOCTYPE html><html><body>hello world</body></html>", {
    headers: { "Content-Type": contentType(".html") },
  });
}));

Warning: Deno flash server (Deno.serve()) is an unstable API (as of v1.25). The API may change and stop working.

Warning: This library manually implements the HTTP/1.1 protocol. (Look at the source code!) I’m testing it, but it may contain bugs. Also, don’t expect performance.

Warning: I am currently using a generator to return multiple responses. However, we may change how we use it in the future.