import { etag } from "https://deno.land/x/oak@v14.1.1/mod.ts";
const { ifMatch } = etag;
A helper function that takes the value from the If-Match
header and a
calculated etag for the target. By using strong comparison, return true
if
the values match, otherwise false
.
See MDN's If-Match
article for more information on how to use this function.
import {
calculate,
ifMatch,
} from "https://deno.land/std@0.224.0/http/etag.ts";
import { assert } from "https://deno.land/std@0.224.0/assert/assert.ts"
const body = "hello deno!";
Deno.serve(async (req) => {
const ifMatchValue = req.headers.get("if-match");
const etag = await calculate(body);
assert(etag);
if (!ifMatchValue || ifMatch(ifMatchValue, etag)) {
return new Response(body, { status: 200, headers: { etag } });
} else {
return new Response(null, { status: 412, statusText: "Precondition Failed"});
}
});