letchin

A minimal HTTP framework built from the ground up using Node’s net module. letchin provides a simple and lightweight approach to building web servers without relying on Node’s built-in http module.

This is the early foundation of a low-level framework inspired by Express and Koa, but implemented entirely from scratch for educational and experimental development.

Installation

npm install letchin

Example Usage

const { tchintchin, mid } = require("letchin");

mid.add("logger", (req, res, next) => {
  console.log(`[${req.method}] ${req.path}`);
  next();
});

const app = tchintchin();

app.route("GET", "/", mid.logger, (req, res) => {
  res.send("Welcome to letchin");
});

app.route("POST", "/data", (req, res) => {
  console.log("Body:", req.body);
  res.send("Data received");
});

app.listen(3000, () => console.log("Server running on port 3000"));

API Overview

tchintchin()

Creates a new application instance.

Methods

| Method | Description | |---------|--------------| | app.route(method, path, ...middlewares, handler) | Define a route with optional middlewares and a final handler. | | app.listen(port, callback) | Start the server on a given port. |

Middleware System

letchin includes a simple middleware manager.

Example

mid.add("auth", (req, res, next) => {
  if (req.get("authorization") !== "secret") {
    res.statusCode = 401;
    res.send("Unauthorized");
  } else next();
});

app.route("GET", "/private", mid.auth, (req, res) => {
  res.send("Access granted");
});

Notes

• Middleware functions receive (req, res, next).
• You can define custom middlewares using mid.add(name, fn).
• Middlewares are executed in order; call next() to continue.

Request Object (req)

Each route handler and middleware receives a req object representing the HTTP request.

| Property | Type | Description | |-----------|------|-------------| | req.method | string | HTTP method (e.g. GET, POST) | | req.path | string | URL path | | req.headers | object | Parsed request headers | | req.body | string | Raw request body | | req.get(name) | function | Returns a header value by name | | req.is(type) | function | Checks if Content-Type contains a given string |

Response Object (res)

Each handler also receives a res object used to send responses.

| Method | Description | |---------|--------------| | res.send(body) | Sends an HTTP response with status 200 and default headers. | | res.statusCode | Property used to set custom status codes before sending. |

Example

app.route("GET", "/custom", (req, res) => {
  res.statusCode = 201;
  res.send("Created");
});

Current Limitations

letchin is still under active minimal development. Current limitations include:

• No query parameter or URL parameter parsing
• No JSON auto-parsing middleware
• No response helpers like .json() or .set()
• Only handles one request per connection (no Keep-Alive yet)
• Error handling is basic and synchronous

Roadmap

• Add .status() and .set() to response
• Add URL parameter parsing
• Add middleware chaining improvements
• Add async body parsing and streaming
• Introduce a testing utility and logging layer

License

Creative Commons Attribution–NonCommercial 4.0 International (CC BY-NC 4.0) © 2025 Oussama Benoujja

You may share and adapt this work for non-commercial purposes, provided that appropriate credit is given. For the full license text, see Creative Commons License.