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Deno Fetch Event Adapter

Dispatches global fetch events using Deno’s http module.

It is mostly intended as a temporary solution until Deno implements the Service Worker spec directly.

It works fine for local testing, developing Cloudflare Workers while offline, and similar use cases. However, production use is not recommended.


// file: 'mod.ts'
import '';

if (typeof FetchEvent !== 'undefined') console.log(true);

self.addEventListener('fetch', event => {
  event.respondWith(new Response('Hello World', { 
    status: 200, 
    headers: [['content-type', 'text/plain']],

Your script needs the --allow-net permission and also requires a --location:

deno run --allow-net --location=http://localhost:8000 mod.ts

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

deno run --allow-net --allow-read --location=https://localhost:8000 mod.ts \
  --cert=./path/to/localhost.key \

For more, see Deno’s http module documentation.