🛠️ Pnyx - Type-Safe Configuration Loader

A lightweight, zero-dependency configuration loader for Node.js applications, written in TypeScript.

Load your configuration from environment variables based on a predefined schema, with type validation and parsing, into a strongly-typed, immutable configuration object.

Built with modern JavaScript and packaged in both CommonJS and ES Modules formats for seamless integration.

Fun fact: Made in under 3 hours, based on the premise of my existing configuration loader snippet from NiceBadge.

Why Pnyx? Just as the ancient Athenians gathered on the Pnyx hill to debate, establish laws, and bring order to their city, this library serves as the assembly point for your application's configuration. Define your essential settings and rules – the "laws" – within a clear schema, and pnyx ensures they are correctly gathered, validated, and assembled into the stable, foundational configuration your application needs to operate decisively.

Features

• 🪶 Super Tiny — Runtime size of ~4.7KB, 17.5KB total artifact size.
• 🗺️ Schema-Based Loading — Define the structure, types, and requirements of your config using a TypeScript object.
• ✅ Validation & Parsing — Automatically parses environment variables into desired types and validates type consistency.
• 🔀️ Default Values — Provide fallback values for missing environment variables.
• 🤝 Static Constants — Merge your predefined constants alongside dynamically loaded environment variables.
• ⚠️ Customizable Error Handling — Callbacks (onWarn and onError) to customize how errors and warnings are handled.
• 🧊 Immutability — Frozen final configuration object prevents accidental modifications.
• 💎 Zero External Dependencies — Written in TypeScript, without external libraries.

How to use?

1. Install

npm install pnyx

2. Define your schema and constants

With TypeScript:

// config.ts
import {Pnyx, ConfigSchema, PnyxConfig} from "pnyx";

// Your configuration, loaded and built from environment variables
const schema = {
	app: {
		port: {type: 'number', required: true},
		host: {default: 'localhost'},
	},
	database: {
		host: {varName: "DB_HOST", default: "localhost"},
		user: {varName: "DB_USER", required: true},
		pass: {varName: "DB_PASS", required: true},
	},
} as const satisfies ConfigSchema;

// Your own properties that will be attached to the config
const constants = {
	serviceName: "MyCoolService",
	apiVersion: 1,
} as const;

export const config: PnyxConfig<typeof schema, typeof constants> = Pnyx(schema, {constants});

Without TypeScript (CommonJS)

// config.ts
const {Pnyx} = require("pnyx")

// Your configuration, loaded and built from environment variables
const schema = {
	app: {
		port: {type: 'number', required: true},
		host: {default: 'localhost'},
	},
	database: {
		host: {varName: "DB_HOST", default: "localhost"},
		user: {varName: "DB_USER", required: true},
		pass: {varName: "DB_PASS", required: true},
    },
};

// Your own properties that will be attached to the config
const constants = {
    serviceName: "MyCoolService",
    apiVersion: 1,
};

module.exports = Pnyx(schema, {constans});

3. Use in your code

// todo