Deno Fetch Event Adapter

Deno Fetch Event Adapter

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

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

• Example
• Error Handling

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

// file: "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);
});

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Links: GitHub | ghuc.cc · NPM | Browse Package · deno.land | Docs

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