HTTP and Fetch

Built-in HTTP server and fetch client patterns for APIs and microservices. Results appear in the same fence: same-line // comments when short, multiline // blocks below the sample when not.

http createServer

Minimal HTTP server with the built-in module.

import http from "node:http";
const server = http.createServer((req, res) => {
  res.writeHead(200, { "content-type": "text/plain" });
  res.end("ok");
});
// server.listen(3000) -> GET / responds "ok"
typeof server.listen  // "function"

fetch JSON GET

Global fetch (undici) is available in modern Node for outbound HTTP.

const res = await fetch("data:application/json,{\"ok\":true}");
res.ok  // true
await res.json()
// { ok: true }

fetch POST JSON

Send JSON with method, headers, and stringified body.

const body = JSON.stringify({ name: "Ada" });
JSON.parse(body).name  // "Ada"
// await fetch(url, {
//   method: "POST",
//   headers: { "content-type": "application/json" },
//   body,
// });

Request headers

Read incoming headers on the server; treat them as lowercase names.

import http from "node:http";
// inside createServer:
// const auth = req.headers.authorization;
const headers = { authorization: "Bearer x" };
headers.authorization  // "Bearer x"

URL Parse Query

Use the WHATWG URL API for paths and search params.

const u = new URL("/items?page=2", "http://localhost");
u.pathname              // "/items"
u.searchParams.get("page")  // "2"

Abort fetch Timeout

Cancel slow clients with AbortSignal timeouts.

const signal = AbortSignal.timeout(5_000);
signal.aborted  // false
// await fetch(url, { signal });

Stream Response Body

Consume a fetch body as text, JSON, or arrayBuffer.

const res = await fetch("data:text/plain,hello");
await res.text()  // "hello"

Set multiple cookies by calling append on Headers.

const headers = new Headers();
headers.append("set-cookie", "a=1; Path=/");
headers.append("set-cookie", "b=2; Path=/");
headers.getSetCookie?.().length ?? [...headers].filter(([k]) => k === "set-cookie").length
// 2

https request TLS

Use https or fetch for TLS; configure certs via env or undici options when needed.

import https from "node:https";
typeof https.get  // "function"
// https.get("https://example.com", (res) => res.pipe(process.stdout));

JSON Body Server

Read and parse a JSON body from an IncomingMessage carefully with size limits in production.

async function readJson(chunks: Buffer[]) {
  return JSON.parse(Buffer.concat(chunks).toString("utf8"));
}
await readJson([Buffer.from('{"a":1}')])
// { a: 1 }

Status and end

Always end the response; use correct status codes for errors.

const payload = JSON.stringify({ error: "not_found" });
payload  // '{"error":"not_found"}'
// res.writeHead(404, { "content-type": "application/json" });
// res.end(payload);

Keep Alive Server

HTTP keep-alive is default - set timeouts for hanging sockets.

import http from "node:http";
const server = http.createServer();
server.keepAliveTimeout = 5_000;
server.headersTimeout = 6_000;
server.keepAliveTimeout  // 5000

FormData upload

Multipart uploads use FormData with fetch.

const form = new FormData();
form.set("name", "Ada");
form.get("name")  // "Ada"
// form.set("file", new Blob([buf]), "a.bin");
// await fetch(url, { method: "POST", body: form });

Undici Agent note

Tune connection pooling via undici Agent for high-volume clients when defaults are insufficient.

// import { Agent, setGlobalDispatcher } from "undici";
// setGlobalDispatcher(new Agent({ connections: 32 }));
// pools keep-alive connections to the same host

WebSocket undici

WebSockets are available via undici/ws ecosystems - pick one stack and stick to it.

// const ws = new WebSocket("ws://localhost:3000");
// ws.addEventListener("message", (ev) => console.log(ev.data));
typeof WebSocket !== "undefined"  // true on modern Node

Streams and Pipelines - streaming bodies
Errors and Debugging - HTTP error handling
Async Patterns - concurrent requests

Node.js API Documentation - Complete reference for core modules and APIs.
MDN Web Docs – Express/Node.js - Beginner-to-intermediate Express/Node tutorials.
Express.js - Official Express site and guides.
Node.js Cookbook, 5th Edition - Practical server-side recipes.
Node.js in Action, 2nd Edition - Classic practical Node.js.

Stack versions: Node.js 24.18.0 (LTS line 24) · TypeScript 5.6+ · npm 10+

HTTP and Fetch

Built-in HTTP server and fetch client patterns for APIs and microservices. Results appear in the same fence: same-line // comments when short, multiline // blocks below the sample when not.

http createServer

Minimal HTTP server with the built-in module.

import http from "node:http";
const server = http.createServer((req, res) => {
  res.writeHead(200, { "content-type": "text/plain" });
  res.end("ok");
});
// server.listen(3000) -> GET / responds "ok"
typeof server.listen  // "function"

fetch JSON GET

Global fetch (undici) is available in modern Node for outbound HTTP.

const res = await fetch("data:application/json,{\"ok\":true}");
res.ok  // true
await res.json()
// { ok: true }

fetch POST JSON

Send JSON with method, headers, and stringified body.

const body = JSON.stringify({ name: "Ada" });
JSON.parse(body).name  // "Ada"
// await fetch(url, {
//   method: "POST",
//   headers: { "content-type": "application/json" },
//   body,
// });

Request headers

Read incoming headers on the server; treat them as lowercase names.

import http from "node:http";
// inside createServer:
// const auth = req.headers.authorization;
const headers = { authorization: "Bearer x" };
headers.authorization  // "Bearer x"

URL Parse Query

Use the WHATWG URL API for paths and search params.

const u = new URL("/items?page=2", "http://localhost");
u.pathname              // "/items"
u.searchParams.get("page")  // "2"

Abort fetch Timeout

Cancel slow clients with AbortSignal timeouts.

const signal = AbortSignal.timeout(5_000);
signal.aborted  // false
// await fetch(url, { signal });

Stream Response Body

Consume a fetch body as text, JSON, or arrayBuffer.

const res = await fetch("data:text/plain,hello");
await res.text()  // "hello"

Set multiple cookies by calling append on Headers.

const headers = new Headers();
headers.append("set-cookie", "a=1; Path=/");
headers.append("set-cookie", "b=2; Path=/");
headers.getSetCookie?.().length ?? [...headers].filter(([k]) => k === "set-cookie").length
// 2

https request TLS

Use https or fetch for TLS; configure certs via env or undici options when needed.

import https from "node:https";
typeof https.get  // "function"
// https.get("https://example.com", (res) => res.pipe(process.stdout));

JSON Body Server

Read and parse a JSON body from an IncomingMessage carefully with size limits in production.

async function readJson(chunks: Buffer[]) {
  return JSON.parse(Buffer.concat(chunks).toString("utf8"));
}
await readJson([Buffer.from('{"a":1}')])
// { a: 1 }

Status and end

Always end the response; use correct status codes for errors.

const payload = JSON.stringify({ error: "not_found" });
payload  // '{"error":"not_found"}'
// res.writeHead(404, { "content-type": "application/json" });
// res.end(payload);

Keep Alive Server

HTTP keep-alive is default - set timeouts for hanging sockets.

import http from "node:http";
const server = http.createServer();
server.keepAliveTimeout = 5_000;
server.headersTimeout = 6_000;
server.keepAliveTimeout  // 5000

FormData upload

Multipart uploads use FormData with fetch.

const form = new FormData();
form.set("name", "Ada");
form.get("name")  // "Ada"
// form.set("file", new Blob([buf]), "a.bin");
// await fetch(url, { method: "POST", body: form });

Undici Agent note

Tune connection pooling via undici Agent for high-volume clients when defaults are insufficient.

// import { Agent, setGlobalDispatcher } from "undici";
// setGlobalDispatcher(new Agent({ connections: 32 }));
// pools keep-alive connections to the same host

WebSocket undici

WebSockets are available via undici/ws ecosystems - pick one stack and stick to it.

// const ws = new WebSocket("ws://localhost:3000");
// ws.addEventListener("message", (ev) => console.log(ev.data));
typeof WebSocket !== "undefined"  // true on modern Node

Streams and Pipelines - streaming bodies
Errors and Debugging - HTTP error handling
Async Patterns - concurrent requests

Node.js API Documentation - Complete reference for core modules and APIs.
MDN Web Docs – Express/Node.js - Beginner-to-intermediate Express/Node tutorials.
Express.js - Official Express site and guides.
Node.js Cookbook, 5th Edition - Practical server-side recipes.
Node.js in Action, 2nd Edition - Classic practical Node.js.

Stack versions: Node.js 24.18.0 (LTS line 24) · TypeScript 5.6+ · npm 10+

HTTP and Fetch

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HTTP and Fetch