Valtors

Small, flexible, and extensible validation library for TypeScript/JavaScript. Provides TC39 decorators for classes and properties. Works great with MobX.

Install

yarn add valtors
# or
npm install valtors

Features

• Built-in validators: required, email, min, max, minLength, maxLength, match, oneOf, propEquals, dateString
• Class decorator @validatable injects validate() method and validation errors property
• Property decorators for declarative validation
• Async validation support
• Custom validators and error messages
• TypeScript-first with full type safety

API Overview

Export	Description
required, email, min, max, minLength, maxLength	Built-in validators
match, oneOf, propEquals, dateString	Pattern and comparison validators
validate	Validate an object or a single property
@validatable	Class decorator that adds validation support
Property decorators (@required, @email, etc.)	Declarative property validation
assertions	Low-level assertion functions
messages	Default error messages (customizable)
async/validate	Async version of validate

Usage

Basic validation with decorators

import { observable, action, makeObservable } from 'mobx';
import { validatable, required, email } from 'valtors/decorators';

@validatable
class AuthStore {
  @required()
  @email()
  accessor username = '';

  @required({ message: 'Password is required' })
  accessor password = '';

  constructor() {
    makeObservable(this, {
      username: observable,
      password: observable,
      submit: action,
    });
  }

  submit(): void {
    if (!this.validate()) return;
    // all fields valid, proceed
  }
}

Custom validation errors property

import { validatable } from 'valtors/decorators';

@validatable({ resultProperty: 'errors' })
class FormStore {
  // ...
  // errors will be available as `this.errors` instead of `this.validationErrors`
}

Programmatic validation (without decorators)

import { validate } from 'valtors';
import { required, email, minLength } from 'valtors';

const validators = {
  username: [required(), email()],
  password: [required(), minLength(8)],
};

const data = { username: 'test', password: '123' };
const result = validate(data, validators);
// result.username.error / result.password.error

Custom validator

import type { Validator, ValueAssertion } from 'valtors';

function noSpaces(message = 'Must not contain spaces'): Validator<ValueAssertion<string>> {
  return {
    type: 'error',
    message,
    assertion: (value: string) => !value.includes(' '),
  };
}

License

MIT

Repository

https://github.com/vlazh/valtors