schema-sync-validator

A lightweight, zero-dependency, chainable data validation library for Node.js and browsers. A faster and simpler alternative to Zod and Joi, designed for both frontend form validation and backend API validation from a single schema definition.

Features

• 🚀 Zero dependencies — extremely lightweight and fast.
• ⛓️ Chainable API — fluent, readable schema definitions (.string().min(3).max(50).email()).
• 🧩 Rich Type Support — built-in schemas for strings, numbers, booleans, dates, arrays, and nested objects.
• ✅ Validation + Transformation — validate and transform data in one pass (.trim(), .lowercase(), .transform()).
• 📦 Object Utilities — .extend(), .pick(), .omit(), .strict(), and .passthrough() for flexible object schemas.
• 🏷️ Custom Labels — .label('Email Address') for user-friendly error messages.
• 🎯 Custom Rules — .refine(fn, msg) for any custom validation logic.
• 🔧 Defaults — .default(value) for fallback values.
• ❓ Optional & Nullable — .optional() and .nullable() support.

Installation

npm install schema-sync-validator

Quick Start

const v = require('schema-sync-validator');

// Define a user registration schema
const registerSchema = v.object({
  username: v.string().min(3).max(20).trim().lowercase(),
  email: v.string().email().label('Email Address'),
  password: v.string().min(8, 'Password must be at least 8 characters.'),
  age: v.number().integer().min(13).optional(),
  role: v.string().enum(['user', 'admin']).default('user'),
  tags: v.array(v.string()).nonempty().optional()
});

// Validate input data
const result = registerSchema.validate({
  username: '  JohnDoe  ',
  email: '[email protected]',
  password: 'secure123',
  age: 25
});

if (result.success) {
  console.log('Valid data:', result.data);
  // { username: 'johndoe', email: '[email protected]', password: 'secure123', age: 25, role: 'user' }
} else {
  console.log('Errors:', result.errors);
}

Schema Types

String

v.string()
  .min(3)            // Minimum length
  .max(100)          // Maximum length
  .email()           // Must be valid email
  .url()             // Must be valid URL
  .pattern(/regex/)  // Must match regex
  .enum(['a', 'b'])  // Must be one of
  .nonempty()        // Cannot be empty string
  .trim()            // Auto-trim whitespace
  .lowercase()       // Auto-lowercase
  .uppercase()       // Auto-uppercase

Number

v.number()
  .min(0)       // Minimum value
  .max(1000)    // Maximum value
  .integer()    // Must be integer
  .positive()   // Must be > 0
  .port()       // Valid port (1-65535)

Boolean, Date

v.boolean()
v.date().min('2020-01-01').max('2030-12-31')

Array

v.array(v.string())    // Array of strings
  .min(1)              // Min items
  .max(10)             // Max items
  .nonempty()          // Cannot be empty

Object

const userSchema = v.object({
  name: v.string(),
  email: v.string().email()
});

// Utilities
userSchema.strict()                       // Disallow unknown keys
userSchema.passthrough()                  // Allow & preserve unknown keys
userSchema.extend({ age: v.number() })    // Add new fields
userSchema.pick(['name'])                 // Keep only specified fields
userSchema.omit(['email'])                // Remove specified fields

Common Methods (All Types)

.optional()         // undefined is OK
.nullable()         // null is OK
.default('value')   // Fallback if undefined
.label('Field')     // Custom error label
.transform(fn)      // Transform after validation
.refine(fn, msg)    // Custom validation rule

License

MIT