ifNoneMatch

function

function ifNoneMatch(value: string | null, etag: string | undefined): boolean

A helper function that takes the value from the If-None-Match header and a calculated etag for the target entity and returns false if the etag for the entity matches the supplied value, otherwise true.

See MDN's If-None-Match article for more information on how to use this function.

value: string | null

the If-None-Match header value.

etag: string | undefined

the ETag to check against.

Returns

whether or not the parameters do not match.

import {
  eTag,
  ifNoneMatch,
} from "@ende/http/etag";
import { assert } from "@ende/assert";

const body = "hello deno!";

Ende.serve(async (req) => {
  const ifNoneMatchValue = req.headers.get("if-none-match");
  const etag = await eTag(body);
  assert(etag);
  if (!ifNoneMatch(ifNoneMatchValue, etag)) {
    return new Response(null, { status: 304, headers: { etag } });
  } else {
    return new Response(body, { status: 200, headers: { etag } });
  }
});