Cache Tags using Workers

export default {
  async fetch(request): Promise<Response> {
    const requestUrl = new URL(request.url);
    const params = requestUrl.searchParams;
    const tags =
      params && params.has("tags") ? params.get("tags").split(",") : [];
    const url =
      params && params.has("uri") ? JSON.parse(params.get("uri")) : "";
    if (!url) {
      const errorObject = {
        error: "URL cannot be empty",
      };
      return new Response(JSON.stringify(errorObject), { status: 400 });
    }
    const init = {
      cf: {
        cacheTags: tags,
      },
    };
    return fetch(url, init)
      .then((result) => {
        const cacheStatus = result.headers.get("cf-cache-status");
        const lastModified = result.headers.get("last-modified");
        const response = {
          cache: cacheStatus,
          lastModified: lastModified,
        };
        return new Response(JSON.stringify(response), {
          status: result.status,
        });
      })
      .catch((err) => {
        const errorObject = {
          error: err.message,
        };
        return new Response(JSON.stringify(errorObject), { status: 500 });
      });
  },
} satisfies ExportedHandler;

from pyodide.ffi import to_js as _to_js
from js import Response, URL, Object, fetch

def to_js(x):
    return _to_js(x, dict_converter=Object.fromEntries)

async def on_fetch(request):
    request_url = URL.new(request.url)
    params = request_url.searchParams
    tags = params["tags"].split(",") if "tags" in params else []
    url = params["uri"] or None

    if url is None:
        error = {"error": "URL cannot be empty"}
        return Response.json(to_js(error), status=400)

    options = {"cf": {"cacheTags": tags}}
    result = await fetch(url, to_js(options))

    cache_status = result.headers["cf-cache-status"]
    last_modified = result.headers["last-modified"]
    response = {"cache": cache_status, "lastModified": last_modified}

    return Response.json(to_js(response), status=result.status)