veruniq — Declarative Form Validator

A small, framework-agnostic JavaScript form validation library that supports declarative schemas, synchronous and asynchronous rules, nested path access, presets, and custom messages. Lightweight and easy to embed in Node or browser bundles.

Install

# from npm (if published)
npm install veruniq

# or use locally
npm install

Quick Start

const { createValidator, registerPreset } = require('./index');

// optional: register a preset
registerPreset('strongPassword', [
  'minLength:8',
  { rule: 'pattern:^(?=.*[A-Z])(?=.*\\d).+$', message: 'Password must include an uppercase letter and a digit' }
]);

const schema = {
  'user.email': ['required', 'email'],
  'password': ['required', 'minLength:6', 'preset:strongPassword'],
  'age': [{ rule: 'min:18', message: 'You must be at least 18' }]
};

const validator = createValidator(schema, { abortEarly: true });

(async () => {
  const { valid, errors } = await validator.validate({
    user: { email: '[email protected]' },
    password: 'Secret1',
    age: 20
  });

  console.log(valid, errors);
  // { valid: true, errors: {} }
})();

API

• Entry point: index.js
• createValidator(schema, options) — main factory (see createValidator)
  • options: { abortEarly: boolean (default true), messages: {} }
  • returns an object with .validate(values) => Promise<{ valid, errors }>

Exports:

• createValidator
• registerPreset
• built-in rules
• default messages
• async helpers asyncUtils

Core behavior:

• Supports rule formats: string shorthand (e.g., min:3), object ({ rule, params, message, when }), or custom function (sync or async).
• Conditional rules via when or dependsOn.
• Presets allow composing multiple rules under a name (preset:NAME).

Schema examples

• String shorthand: "required", "email", "min:18", "pattern:^\\d+$"
• Object rule:

{ rule: 'minLength:6', message: 'Too short' }

• Function rule (sync or Promise-returning):

async (value, ctx) => {
  const ok = await checkUniqueEmail(value);
  return ok || 'Email already taken';
}

Files of interest

• Entry / public API: index.js
• Core validator: src/core.js — schema normalization and execution
• Built-in rule implementations: src/rules.js
• Messages map: src/messages.js
• Preset registry: src/presets.js
• Async helpers: src/asyncUtils.js
• Utility helpers: src/utils.js

Testing

Run provided tests (if dependencies installed):

npm test

Unit tests and examples are located under the repository test/ and src/example/ (if present).

Contributing

• Fork the repository, create a branch, add tests for new behavior, and submit a PR.
• Follow existing code style and keep changes minimal and backwards compatible.

License

MIT — see package.json for license field.