validatejs.org

What It Is

Validate.js is a declarative validation library for validating JavaScript objects. Its core goal is to avoid tight coupling with any specific framework or language, allowing validation constraints to be described in JSON and shared between the client and server. The project is hosted on GitHub and released under the MIT License. Its documentation states that it is unit-tested, has 100% code coverage, and is suitable for production use.

Core Capabilities

It supports any ECMAScript 5.1 runtime and can run in both browsers and Node.js. Modern browsers as well as IE9+ are supported. Installation options include CDN, Require.js/AMD, npm, Bower, and Component, and you can also download the development version or minified production build for self-hosting. Built-in validators cover common scenarios such as date/datetime, email, equality, exclusion, format, inclusion, length, numericality, presence, type, URL, and more. On the API side, it provides validate, validate.async, and validate.single, with support for regular objects, collecting values from form elements, single-value validation, limited dot-notation nested validation, and grouped, flat, detailed, or custom error formats.

Pricing and Open Source

The text clearly states that Validate.js is an open-source component from Wrapp and is released under the MIT License. There is no mention of any commercial edition, subscription, or paid service. Its pricing model can therefore be regarded as free and open source.

Pros and Cons

Its strengths are that it is lightweight and has no required external dependencies, with the production build only about 5.05KB gzipped. Constraints are represented in JSON, which makes cross-end reuse easier. Its extension mechanism is straightforward: you can add synchronous or asynchronous validators to validate.validators, and you can also replace utility functions and formatters. The documentation covers installation, dependencies, runtime environments, APIs, validators, and examples, with a fairly high density of information.

The limitations are also fairly clear: most validators treat null and undefined as valid by default, so required fields must be explicitly declared with presence, which can easily trip up beginners. Support for nested objects is relatively basic, and complex conditional validation is better handled by splitting schemas. Date and datetime validation requires you to configure parse/format yourself, and usually also involves introducing a library such as moment.js. Asynchronous validation requires an A+ Promise and is not compatible with jQuery Promise. The version mentioned in the text is 0.13.1, so recent maintenance activity cannot be determined.

Who It’s For and Access in China

Validate.js is suitable for teams that need lightweight form validation, Node.js object validation, shared validation rules between frontend and backend, and no binding to a specific framework. For TypeScript strongly typed schemas, complex nested models, or large ecosystem integrations, it may be worth comparing Zod, Yup, Joi, or Ajv. The text does not provide information about access from China, so this remains unknown.