Validate-Seip

A lightweight, framework-agnostic JavaScript validation library with built-in internationalization support for Express.js, Next.js, SvelteKit, and other Node.js frameworks.

Features

• ✅ Framework Agnostic - Works with Express.js, Next.js, SvelteKit, and any framework that uses request/response patterns
• 🌍 Multi-language Support - Built-in support for English, Spanish, Portuguese, and French
• 🎯 Comprehensive Validation Rules - Email, URL, password strength, numeric, alpha, alphanumeric, date, and more
• 🔧 Customizable Messages - Override default messages with your own
• 🚀 Zero Dependencies - Lightweight and fast
• 📦 ES Module - Modern JavaScript module system

Installation

npm i @seip/validate

Quick Start

import { Validator } from '@seip/validate';

// Define your validation schema
const userSchema = {
    email: { required: true, email: true },
    password: { required: true, password: true, min: 6 },
    name: { required: true, min: 3, max: 50 },
    age: { number: true },
    website: { url: true },
    role: { in: ['admin', 'user', 'guest'] },
    terms: { boolean: true, equals: true }
};

// Create a validator instance
const validator = new Validator(userSchema, 'en');

// Validate a request
const result = await validator.validate(req);

if (!result.success) {
    console.log(result.errors); // Array of error messages
}

Usage Examples

Express.js Middleware

import express from 'express';
import { Validator } from '@seip/validate';

const app = express();
app.use(express.json());

const loginSchema = {
    email: { required: true, email: true },
    password: { required: true, min: 6 }
};

const loginValidator = new Validator(loginSchema, 'en');

app.post('/login', loginValidator.middleware(), (req, res) => {
    res.json({ message: 'Login successful' });
});

Next.js API Route

import { Validator } from '@seip/validate';

const registerSchema = {
    email: { required: true, email: true },
    password: { required: true, password: true },
    name: { required: true, min: 3 }
};

export default async function handler(req, res) {
    const validator = new Validator(registerSchema, 'en');
    const result = await validator.validate(req);
    
    if (!result.success) {
        return res.status(400).json(result);
    }
    
    // Process registration...
    res.status(200).json({ message: 'Registration successful' });
}

SvelteKit

import { Validator } from '@seip/validate';

const profileSchema = {
    name: { required: true, min: 3, max: 50 },
    bio: { max: 500 },
    website: { url: true }
};

export const actions = {
    default: async ({ request }) => {
        const formData = await request.formData();
        const req = {
            body: Object.fromEntries(formData)
        };
        
        const validator = new Validator(profileSchema, 'en');
        const result = await validator.validate(req);
        
        if (!result.success) {
            return { errors: result.errors };
        }
        
        // Process form...
        return { success: true };
    }
};

Validation Rules

| Rule | Description | Example | |------|-------------|---------| | required | Field must be present and not empty | { required: true } | | min | Minimum string length | { min: 6 } | | max | Maximum string length | { max: 50 } | | email | Valid email format | { email: true } | | number | Numeric value | { number: true } | | alpha | Only letters (a-z, A-Z) | { alpha: true } | | alphanumeric | Letters and numbers only | { alphanumeric: true } | | boolean | Boolean value | { boolean: true } | | date | Valid ISO 8601 date | { date: true } | | url | Valid URL format | { url: true } | | in | Value must be in array | { in: ['admin', 'user'] } | | equals | Value must equal specific value | { equals: true } | | password | Strong password (uppercase, lowercase, numbers, min 6 chars) | { password: true } | | pattern | Custom regex pattern | { pattern: /^[A-Z]/ } |

Supported Languages

The library supports the following languages out of the box:

• English (en)
• Spanish (es)
• Portuguese (pt)
• French (fr)

Setting Language

// Set language explicitly
const validator = new Validator(schema, 'en');

// Use session language (falls back to Spanish if not set)
const validator = new Validator(schema);
const result = await validator.validate(req); // Uses req.session.lang if available

Custom Error Messages

You can override default error messages in two ways:

1. Per-field Custom Messages

const schema = {
    email: {
        required: true,
        email: true,
        messages: {
            required: 'Please provide your email address',
            email: 'That doesn\'t look like a valid email'
        }
    }
};

2. Global Custom Messages

const customMessages = {
    en: {
        required: (field) => `${field} is mandatory`,
        email: (field) => `Please enter a valid email for ${field}`,
        // ... other rules
    }
};

const validator = new Validator(schema, 'en', customMessages);

Response Format

Success Response

{
    success: true,
    errors: [],
    message: [],
    html: []
}

Error Response

{
    success: false,
    errors: [
        "email is required",
        "password must be at least 6 characters"
    ],
    message: [
        "email is required",
        "password must be at least 6 characters"
    ],
    html: [
        '<p class="text-red-500 text-danger">email is required</p>',
        '<p class="text-red-500 text-danger">password must be at least 6 characters</p>'
    ]
}

Advanced Examples

Combining Multiple Rules

const schema = {
    username: {
        required: true,
        alphanumeric: true,
        min: 3,
        max: 20
    },
    password: {
        required: true,
        password: true,
        min: 8
    },
    confirmPassword: {
        required: true,
        equals: req.body.password // Must match password field
    }
};

Custom Pattern Validation

const schema = {
    zipCode: {
        required: true,
        pattern: /^\d{5}(-\d{4})?$/ // US ZIP code format
    },
    phoneNumber: {
        pattern: /^\+?[\d\s-()]+$/ // International phone format
    }
};

Testing

Run the included test suite:

node test.js

The test file demonstrates validation in all supported languages with various scenarios.

API Reference

Validator Class

Constructor

new Validator(schema, lang_default = null, messages = null)

• schema (Object): Validation schema defining rules for each field
• lang_default (String, optional): Default language code ('en', 'es', 'pt', 'fr')
• messages (Object, optional): Custom error messages object

Methods

validate(req)

Validates the request body against the schema.

• Parameters: req - Request object with body property
• Returns: Promise resolving to validation result object

middleware()

Returns an Express.js middleware function that automatically validates and returns 400 status on validation failure.

• Returns: Express middleware function

License

MIT

Author

Seip25

Repository

https://github.com/seip25/validate

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Support

For issues and questions, please use the GitHub Issues page.