Create a dynamic dispatch Worker

src/index.js
export default {
	async fetch(request, env) {
		try {
			// parse the URL, read the subdomain
			let workerName = new URL(request.url).host.split('.')[0];
			let userWorker = env.dispatcher.get(workerName);
			return await userWorker.fetch(request);
		} catch (e) {
			if (e.message.startsWith('Worker not found')) {
				// we tried to get a worker that doesn't exist in our dispatch namespace
				return new Response('', { status: 404 });
			}

			// this could be any other exception from `fetch()` *or* an exception
			// thrown by the called worker (e.g. if the dispatched worker has
			// `throw MyException()`, you could check for that here).
			return new Response(e.message, { status: 500 });
		}
	},
};