JSON Schema Validator

JSON Schema Validator (JSV) is built on JSON Schema Core.

Supported Versions

• Draft-04
• Draft-06
• Draft-07
• Draft 2019-09

Install

JSV is designed to run in a vanilla node.js environment, but has no dependencies on node.js specific libraries so it can be bundled for the browser. No compilers, preprocessors, or bundlers are used.

Node.js

npm install @hyperjump/json-schema

Browser

When in a browser context, JSV is designed to use the browser's fetch implementation instead of a node.js fetch clone. The Webpack bundler does this properly without any extra configuration, but if you are using the Rollup bundler you will need to include the browser: true option in your Rollup configuration.

  plugins: [
    resolve({
      browser: true
    }),
    commonjs()
  ]

Usage

const JsonSchema = require("@hyperjump/json-schema");


// Example: Inline schema
const schemaJson = {
  "$schema": "https://json-schema.org/draft/2019-09/schema",
  "$id": "http://example.com/schemas/string",
  "type": "string"
}
JsonSchema.add(schemaJson);
const schema = await JsonSchema.get("http://example.com/schemas/string");

// Example: Fetch from the web
const schema = await JsonSchema.get("http://example.com/schemas/string");

// Example: Fetch from file
const schema = await JsonSchema.get("file:///path/to/my/schemas/string.schema.json");

// Example: Validate instance
const output = await JsonSchema.validate(schema, "foo");
if (output.valid) {
  console.log("Instance is valid :-)");
} else {
  console.log("Instance is invalid :-(");
}

// Example: Precompile validator
const isString = await JsonSchema.validate(schema);
const output = isString("foo");

// Example: Specify output format
const output = await JsonSchema.validate(schema, "foo", JsonSchema.VERBOSE);

// Example: Specify meta-validation output format
JsonSchema.setMetaOutputFormat(JsonSchema.FLAG);

// Example: Disable meta-validation
JsonSchema.setShouldMetaValidate(false);

API

• add: (schema: object, url?: URI, schemaVersion?: string) => undefined

  Load a schema. See JSC - $id and JSC - $schema for more information.

• get: (url: URI, contextDoc?: SDoc, recursive: boolean = false) => Promise

  Fetch a schema. Schemas can come from an HTTP request, a file, or a schema that was added with add.

• validate: (schema: SDoc, instance: any, outputFormat: OutputFormat = FLAG) => OutputUnit

  Validate an instance against a schema. The function is curried to allow compiling the schema once and applying it to multiple instances. See

• setMetaOutputFormat: (outputFormat: OutputFormat) => undefined

  Validate an instance against a schema. The function is curried to allow compiling the schema once and applying it to multiple instances.

• setShouldMetaValidate: (isEnabled: boolean) => undefined

  Enable or disable meta-validation.

• OutputFormat: [FLAG | BASIC | DETAILED | VERBOSE]

  JSC - Output for more information on output formats.

Not (yet) Supported

This implementation supports all required features of JSON Schema draft 2019-09. The following optional features are not supported yet.

• The unevaluatedProperties keyword
• The unevaluatedItems keyword
• The format vocabulary

Contributing

Tests

Run the tests

npm test

Run the tests with a continuous test runner

npm test -- --watch