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.   // without awaiting the function
  9.   serveHttp(conn);
  10. }
  12. async function serveHttp(conn: Deno.Conn) {
  13.   // This "upgrades" a network connection into an HTTP connection.
  14.   const httpConn = Deno.serveHttp(conn);
  15.   // Each request sent over the HTTP connection will be yielded as an async
  16.   // iterator from the HTTP connection.
  17.   for await (const requestEvent of httpConn) {
  18.     // The native HTTP server uses the web standard `Request` and `Response`
  19.     // objects.
  20.     const body = `Your user-agent is:\n\n${
  21.       requestEvent.request.headers.get("user-agent") ?? "Unknown"
  22.     }`;
  23.     // The requestEvent's `.respondWith()` method is how we send the response
  24.     // back to the client.
  25.     requestEvent.respondWith(
  26.       new Response(body, {
  27.         status: 200,
  28.       }),
  29.     );
  30.   }
  31. }

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 the stabilization of native HTTP bindings in ^1.13.x, std/http now supports a native HTTP server from ^0.107.0. The legacy server module was removed in 0.117.0.

webserver.ts:

  1. import { serve } from "https://deno.land/std@$STD_VERSION/http/server.ts";
  3. const port = 8080;
  5. const handler = (request: Request): Response => {
  6.   const body = `Your user-agent is:\n\n${
  7.     request.headers.get("user-agent") ?? "Unknown"
  8.   }`;
  10.   return new Response(body, { status: 200 });
  11. };
  13. console.log(`HTTP webserver running. Access it at: http://localhost:8080/`);
  14. await serve(handler, { port });

Then run this with:

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