Simple HTTP web server

Concepts

  • Use Deno’s integrated HTTP server to run your own web server.

Overview

With just a few lines of code you can run your own HTTP web server with control over the response status, request headers and more.

Sample web server

In this example, the user-agent of the client is returned to the client:

webserver.ts:

  1. // Start listening on port 8080 of localhost.
  2. const server = Deno.listen({ port: 8080 });
  3. console.log(`HTTP webserver running.  Access it at:  http://localhost:8080/`);
  5. // Connections to the server will be yielded up as an async iterable.
  6. for await (const conn of server) {
  7.   // In order to not be blocking, we need to handle each connection individually
  8.   // in its own async function.
  9.   (async () => {
  10.     // This "upgrades" a network connection into an HTTP connection.
  11.     const httpConn = Deno.serveHttp(conn);
  12.     // Each request sent over the HTTP connection will be yielded as an async
  13.     // iterator from the HTTP connection.
  14.     for await (const requestEvent of httpConn) {
  15.       // The native HTTP server uses the web standard `Request` and `Response`
  16.       // objects.
  17.       const body = `Your user-agent is:\n\n${requestEvent.request.headers.get(
  18.         "user-agent",
  19.       ) ?? "Unknown"}`;
  20.       // The requestEvent's `.respondWith()` method is how we send the response
  21.       // back to the client.
  22.       requestEvent.respondWith(
  23.         new Response(body, {
  24.           status: 200,
  25.         }),
  26.       );
  27.     }
  28.   })();
  29. }

Then run this with:

  1. deno run --allow-net webserver.ts

Then navigate to http://localhost:8080/ in a browser.

Using the std/http library

ℹ️ Since stabilization of native HTTP server in 1.13, usage of std/http is discouraged. The module is planned to be deprecated in the future releases.

webserver.ts:

  1. import { serve } from "https://deno.land/std@$STD_VERSION/http/server.ts";
  3. const server = serve({ port: 8080 });
  4. console.log(`HTTP webserver running.  Access it at:  http://localhost:8080/`);
  6. for await (const request of server) {
  7.   let bodyContent = "Your user-agent is:\n\n";
  8.   bodyContent += request.headers.get("user-agent") || "Unknown";
  10.   request.respond({ status: 200, body: bodyContent });
  11. }

Then run this with:

  1. deno run --allow-net webserver.ts