HTTP Server: Routing

An example of a HTTP server that handles requests with different responses based on the incoming URL.

Import the http server from std/http.

import { serve } from "https://deno.land/std@0.175.0/http/server.ts";

URL patterns can be used to match request URLs. They can contain named groups that can be used to extract parts of the URL, e.g. the book ID.

const BOOK_ROUTE = new URLPattern({ pathname: "/books/:id" });

function handler(req: Request): Response {

Match the incoming request against the URL patterns.

  const match = BOOK_ROUTE.exec(req.url);

If there is a match, extract the book ID and return a response.

  if (match) {
    const id = match.pathname.groups.id;
    return new Response(`Book ${id}`);
  }

If there is no match, return a 404 response.

  return new Response("Not found (try /books/1)", {
    status: 404,
  });
}

To start the server on the default port, call `serve` with the handler.

console.log("Listening on http://localhost:8000");
serve(handler);

Run this example locally using the Deno CLI:

deno run --allow-net https://byexample-zn2ebbsv6nbg.deno.dev/http-server-routing.ts

Try this example in a Deno Deploy playground:

Additional resources: