How to validate email addresses with v8n?

Use built-in rules like .string() and .pattern() with a regular expression for email validation, or create a custom rule for more specific checks, as shown in the extensibility examples.

v8n vs Joi or Yup: which should I use?

v8n is better for its fluent, chainable API and lightweight bundle, ideal for client-side validation. Joi is more feature-rich for server-side, and Yup offers better React integration, so choose based on ecosystem needs.

Can v8n handle async validation for API calls?

Yes, v8n supports asynchronous validation with .testAsync(), allowing time-consuming checks like backend verifications, as documented in the async validation section.

How to create custom validation rules in v8n?

Define a function that returns a validator and use v8n.extend() to add it, as demonstrated with the 'foo' example, making it behave like a built-in rule.

Is v8n compatible with TypeScript?

The README doesn't explicitly mention TypeScript, so you may need to rely on community type definitions or manual typing, which could be a drawback for TypeScript-heavy projects.

How to validate nested objects with v8n schema?

Use the .schema() method to define validation rules for each key, supporting nested structures, as shown in the object validation example with the 'id' property.

Open-Awesome

v8n

MITJavaScriptv1.5.1

A fluent, chainable JavaScript validation library with a simple API for validating any data type.

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4.1k stars103 forks0 contributors

What is v8n?

v8n is a JavaScript validation library that provides a fluent, chainable API for validating data of any type, including primitives, arrays, and objects. It solves the problem of writing verbose and complex validation logic by offering an intuitive syntax that reads like English, making it easy to create, reuse, and share validation rules.

Target Audience

JavaScript developers working on frontend or backend applications who need robust, flexible, and maintainable data validation, especially those building forms, APIs, or data processing pipelines.

Value Proposition

Developers choose v8n for its exceptionally fluent API that reduces boilerplate, its support for custom rules and asynchronous validation, and its ability to handle complex validation scenarios with minimal code while maintaining readability and reusability.

Overview

☑️ JavaScript fluent validation library

Use Cases

Best For

Validating form inputs with complex conditional rules
Creating reusable validation modules for API request data
Implementing schema validation for JSON objects or configuration files
Building custom validation rules for domain-specific logic
Performing asynchronous validation like backend checks
Ensuring data integrity in JavaScript applications with readable validation code

Not Ideal For

Projects requiring built-in validation components for React, Vue, or Angular out-of-the-box
Applications needing real-time form validation with automatic debouncing or UI state management
Teams prioritizing validation libraries with extensive third-party plugins or community rule sets
Enterprise environments where validation schemas must integrate tightly with TypeScript for full type inference

Pros & Cons

Pros

Fluent Chainable API

Enables readable, English-like validation chains that reduce boilerplate, as demonstrated in examples where complex rules like 'some.not.uppercase()' are expressed intuitively.

Extensible Custom Rules

Allows seamless integration of user-defined validation functions via .extend(), treating them like built-in rules, shown with the 'foo' custom rule example.

Multiple Validation Modes

Supports boolean tests, exception-based validation, failure lists, and async checks, providing flexibility for different scenarios like backend API validation.

Reusable Validation Modules

Validations can be exported and imported as JavaScript modules, promoting code reuse across projects, illustrated in the 'specialNumber.js' example.

Cons

No Built-in UI Integration

Lacks direct integration with UI frameworks, requiring additional setup for form validation in frontend applications compared to libraries like Formik or Vuelidate.

Limited Ecosystem and Plugins

As a smaller library, it has fewer community-contributed rules or extensions, which might necessitate custom work for niche validation scenarios.

Modifier Complexity Overhead

The fluency comes with a learning curve; understanding how modifiers like 'not' and 'some' interact can be confusing, as noted in examples where order changes meaning significantly.

Frequently Asked Questions

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v8n