Deno Fetch Event Adapter

Dispatches global fetch events using Deno's native HTTP server.

~~It is mostly intended as a temporary solution until Deno implements the Service Worker spec directly.~~
This has been scrapped, but this module works just fine for local testing, developing Cloudflare Workers while offline, and similar use cases.

Example

// filename: "worker.js"
import 'https://deno.land/x/fetch_event_adapter/listen.ts';

// This module adds a global `FetchEvent`
if (typeof FetchEvent !== 'undefined') console.log(true);

// This module also adds global type declarations, s.t. this type-checks:
self.addEventListener('fetch', event => {
  const ip = event.request.headers.get('x-forwarded-for');
  event.respondWith(new Response(`Hello ${ip ?? 'World'}`));
});

Your script needs the --allow-net permissions. It also requires a --location, to know on which port to listen for incoming connections:

deno run --allow-net --location=http://localhost:8000 worker.js

If you set the --location to either HTTPS or port 443, you have to provide a --cert and a --key parameter. Your script will also need the read permission to read the files:

deno run --allow-net --allow-read --location=https://localhost:8000 worker.js \
  --cert=./path/to/cert.pem \
  --key=./path/to/key.pem

Error Handling

If an error occurs during estabslishing a connection (e.g. invalid certificate, etc...), the error is dispatched as a global error event rather then crashing the process. You can add custom logging like this:

self.addEventListener('error', event => {
  console.warn(event.message);
  console.warn(event.error);
});