An HTTP server in JavaScript

createServer, a request handler, and JSON out.

import { createServer } from "node:http";

const routes = {
  "/healthz": () => ({ status: "ok" }),
  "/tours": () => ({ tours: ["basics", "async", "node"] }),
};

const server = createServer((request, response) => {
  const handler = routes[new URL(request.url, "http://localhost").pathname];
  if (!handler) {
    response.writeHead(404, { "Content-Type": "application/json" });
    response.end(JSON.stringify({ error: "not found" }));
    return;
  }
  response.writeHead(200, { "Content-Type": "application/json" });
  response.end(JSON.stringify(handler()));
});

server.listen(0, () => {
  console.log("listening on", server.address().port > 0);
  server.close();
});

How it works

1. The handler gets the request and the response.
2. Write the status and headers before the body.
3. server.close stops accepting, then finishes in flight.

Keywords and builtins used here

• JSON
• const
• from
• if
• import
• return

The run, in numbers

Lines

22

Characters to type

644

Tokens

179

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 98 seconds.

Type this snippet

Step 1 of 3 in Network, step 12 of 18 in Node.js.

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