JS Schema CLI Tool

The command-line tool bin/main.js works with JS Schemas. You can tell it which JS schemas to work with by pointing to a file which exports the schema(s):

List schemas exported by a file

$ node bin/main.js /path/to/my-schemas.js

By default, when it isn't given any other commands, this just prints out the schemas it found:

$ node bin/main.js /path/to/basicTypes.js
JSON Schema IDs:
        /types/confidence
        /types/position/2d
        /types/position/3d

Print the JSON Schema described by a JS Schema

To get the JSON Schema described by a JS Schema, specify the $id of the schema and use the --to-json-schema option:

$ node bin/main.js /path/to/basicTypes.js /types/confidence --to-json-schema
{
  "type": "number",
  "minimum": 0,
  "maximum": 1,
  "description": "the confidence of some measurement",
  "$id": "/types/confidence",
  "$schema": "https://json-schema.org/draft/2020-12/schema"
}

Validate JSON with a JS Schema

To check if some JSON matches the schema described by a JS schema, specify the $id of the schema and pass the JSON data on stdin:

$ echo "0.7" | node bin/main.js /path/to/basicTypes.js /types/confidence
Valid!

If the JSON matched the schema, then the process exits with a successful status code (0) and prints "Valid!" to stdout.

If the JSON doesn't match the schema, then the process exits with an error status code (2) and prints information about the error to stderr.

$ echo "1.1" | node bin/main.js /path/to/basicTypes.js /types/confidence
.../schema.js:300
        throw new ValidationError(name, v, validate.errors, jsonSchema)
              ^

ValidationError: Validation Error: /types/confidence
    at assertValid (.../schema.js:300:15)
    at file:///.../bin/main.js:75:5 {
  badValue: 1.1,
  validationErrors: [
    {
      instancePath: '',
      schemaPath: '#/maximum',
      keyword: 'maximum',
      params: { comparison: '<=', limit: 1 },
      message: 'must be <= 1'
    }
  ],
  expectedSchema: {
    type: 'number',
    minimum: 0,
    maximum: 1,
    description: 'the confidence of some measurement',
    '$id': '/types/confidence',
    '$schema': 'https://json-schema.org/draft/2020-12/schema'
  }
}

Write all JSON schemas to a file

Use --build <outputFolder> to write all JSON schemas to a folder. This can optionally be combined with --to-json-schema-flat to inline any internal $ref references.