Validity

Validity is a lightweight JavaScript validation library inspired by Laravel's rule syntax.
Validate individual fields or full forms with clean, readable rules and friendly error messages.

Installation

npm install @mub22/validity
# or
yarn add @mub22/validity

Usage

Validate a single field

import { validate } from "@mub22/validity";

const result = validate("test@example.com", "required|email");

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

Validate a form (multiple fields)

import { validateForm } from "@mub22/validity";

const data = {
  name: "",
  email: "bad-email",
  password: "123",
};

const rules = {
  name: "required|alpha",
  email: "required|email",
  password: "required|min:6",
};

const result = validateForm(data, rules);

console.log(result);
/*
{
  valid: false,
  errors: {
    name: ['This field is required'],
    email: ['This field must be a valid email address'],
    password: ['Must be at least 6 characters long']
  }
}
*/

Built-in Rules

required
min:length
max:length
email
alpha
numeric

More coming soon.

API Reference

Function	Description
`validate`	Validate a single value and rule string
`validateForm`	Validate an object of values and rules
`rules`	Built-in validation rule set
`locales`	Translatable error messages

Custom Rules

You can define your own validation rules by extending the rules object:

import { rules } from "@mub22/validity";

// Add a custom rule: startsWith
rules.startsWith = (value: any, arg: string) =>
  typeof value === "string" && value.startsWith(arg);

⚠️ Important:

You're modifying the global rule set. This affects all future validations using validate() or validateForm().
Only extend existing objects — do not reassign rules entirely (e.g. rules = {} is unsafe).
For large apps, you can create your own wrapper to isolate custom rules if needed.

Localization

Supports multiple languages (e.g. English, Spanish). Default messages are in English. Custom messages and i18n support are coming in future releases.

Custom translates

You can override or translate default error messages by modifying the locales object:

import { locales } from "@mub22/validity";

// Override the default message for the "required" rule in English
locales.en.required = "Este campo es obligatorio";