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Node Hello – Public API & Developer Documentation

Table of Contents

  1. Introduction
  2. Quick-Start
  3. Server Lifecycle
  4. Public HTTP API
  5. Code Reference (Functions & Components)
  6. Extending the Project
  7. Troubleshooting & FAQ

1. Introduction

This repository contains an ultra-light Node.js application that demonstrates the minimum code required to spin up an HTTP server.
Despite its size, it is production-ready and can be used as a starting point for more complex services.

index.js (13 LOC) ──▶ HTTP server ──▶ "Hello Node!" 🌍

2. Quick-Start

  1. Install dependencies (there are none besides Node.js itself) and start the server:

    npm install   # optional – there are no runtime deps, but keeps lock-file up-to-date
npm start     # or: node index.js

  2. Open your browser or issue a curl request:

    curl http://localhost:3000/
# → Hello Node!

  3. Stop the server with Ctrl + C.

Environment variables:

Variable Default Description
PORT 3000 Port the server listens on.

3. Server Lifecycle

The server is started in index.js using Node's built-in http module.

const http = require('http');
const port = process.env.PORT || 3000;

const server = http.createServer(/* request handler */);
server.listen(port, () => console.log(`Server running on http://localhost:${port}/`));

There is no additional framework involved. All Node versions ≥ 12.x are supported.

4. Public HTTP API

Method Path Query / Body Response Example
GET / – 200 OK – plain-text message Hello Node!\n curl http://localhost:3000/

4.1. Example – cURL

curl -i http://localhost:3000/

Response:

HTTP/1.1 200 OK
Content-Type: text/plain
Date: <timestamp>
Connection: keep-alive
Content-Length: 11

Hello Node!

4.2. Example – JavaScript (Fetch)

const res = await fetch('http://localhost:3000/');
const txt = await res.text(); // → "Hello Node!\n"

5. Code Reference (Functions & Components)

Symbol Location Description
server index.js Instance of http.Server returned by http.createServer.
requestListener(req, res) inline in index.js Handles all incoming requests. Always responds with status 200 and body Hello Node!\n.

5.1. requestListener(req, res)

(req, res) => {
  res.statusCode = 200;       // set HTTP status
  const msg = 'Hello Node!\n';
  res.end(msg);               // send response & close connection
}

Parameters

  • req – IncomingMessage object representing the client's request.
  • res – ServerResponse object used to construct the response.

Returns

undefined – side-effect: writes to res and terminates the request.

6. Extending the Project

Because the current implementation is framework-less, you can evolve it in multiple ways:

  1. Add Routes – Inspect req.url and conditionally handle paths, or switch to a router like Express.
  2. Serve JSON – Change Content-Type and respond with serialized data.
  3. Logging – Plug in morgan or another logger for structured logs.
  4. Static Assets – Use fs.createReadStream to serve files.

7. Troubleshooting & FAQ

Q: I get EADDRINUSE: port 3000 already in use.
A: Either stop the existing process using that port or run PORT=4000 npm start.

Q: How can I deploy this to the cloud?
A: Because there are virtually no external dependencies, this app runs out-of-the-box on Heroku, Render, AWS Elastic Beanstalk, Fly.io, Railway, etc.

© 2024 Node Hello Contributors