VSJ is JSON Schema Validation

💡 Learn more about JSON Schema at json-schema.org.

Why?

Because after using it for years, I came to acknowledge that the current de facto standard library for JSON schema validation in JavaScript apps -- AJV -- is clunky. I thought, "how hard could it be?" Two days later, here we are. As it turns out, not that hard.

I primarily use JSON Schema validation for HTTP requests. For each endpoint, I model the query parameters, path parameters, and request body I expect as a JSON Schema, and I short-circuit processing when this validation fails. It's one of the many stages in a multi-stage request processing pipeline.

Features

• lightweight and minimal -- zero dependencies
• readable implementation -- learn from the source code
• readable errors -- easy to see what failed and why
• comprehensive test suite -- 100% code coverage
• idiomatic usage -- failed validation throws an error
• concurrency-friendly -- tightly scoped for massively parallel usage
• fast -- highly tuned for validation performance
• standard compliant -- IETF draft-bhutton-json-schema-validation-01 (2022-06-16)

Installing

Install VSJ just like you would any other npm package:

npm install vsj

Usage

import { createValidator } from 'vsj';

const validate = createValidator({ type: 'number' });

// throws a validation error
validate('hello world');

// does not throw an error
validate(123);