HTTP content-length header middleware for standard Request and Response.

Middleware for HTTP content-length headers.

RFC 9110, 8.6 Content-Length compliant, safely add or remove content-length header.

For a definition of Universal HTTP middleware, see the http-middleware project.

Middleware is exported by default.

import contentLength from "https://deno.land/x/http_content_length@$VERSION/mod.ts";
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";

declare const request: Request;
const handler = () => new Response("hello");

const response = await contentLength(request, handler);

assertEquals(response.headers.get("content-length"), "5");

Based on RFC 9110, 8.6 Content-Length, it is guaranteed that there is no content-length header in the Response.

• If the Response status code is informational(1XX).
• If the Response status code is no content(204).
• If HTTP request method is CONNECT and Response status code is successful(2XX).

Otherwise, it is guaranteed that the content-length header is in the Response.

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