JSON Schema Compiled checK

npm install jsck
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JSON Schema Compiled ChecK

Fast validation against JSON Schema Draft 3


$ npm install jsck


JSCK is a "compiling" schema validator, meaning that it traverses a schema only once (at instantiation) and generates the functions needed to validate documents against the schema. By doing so, it avoids the need to re-traverse the schema structure for every document it validates. This leads to substantial performance improvements.

For the initial (0.1.x) release, JSCK will only tell you whether a document passes validation, not where it failed or why.

Supports most of JSON Schema Draft 3. Documentation and implementation.


Validator = require("../src/index").draft3

# a schema without an "id" declaration

validator = new Validator
  type: "object"
      type: "object"
          required: true
          type: "string"
          pattern: "^[\\w\\d_]{3,32}$"
          type: "string"

{valid} = validator.validate
    login: "automatthew"
    email: "automatthew@mailinator.com"

console.log "Anonymous schema:", valid

Advanced usage examples


Currently passing the canonical test suite for draft3 except for these items:

  • refRemote (Trying to keep this lib synchronous for v0.1.x)
  • ref
    • remote ref, containing refs itself
  • uniqueItems
  • optional/zeroTerminatedFloats
  • optional/format (some of the regexes borrowed from tdegrunt's validator aren't working for me)
    • validation of date-time strings
    • validation of CSS colors
    • validation of host names

Managing resolution scope with the "id" attribute

JSCK does not support the full range of scope manipulations suggested by drafts 3 and 4. It uses "id" declarations only in these cases:

  • at the top level of a schema, to provide a namespace for schemas not loaded from URIs.
  • non-JSON-pointer fragments ("id": "#user"), which serve merely as aliases for specific subschemas, and are thus convenient and unambiguous.

For more information on the topic of scope manipulation, see this issue: https://github.com/json-schema/json-schema/issues/77.


Results of a simple (probably flawed) benchmark against other libs. 8 iterations. Units are ms.

JSCK: valid document, 400 times { max: 2.596,
  median: 0.494,
  min: 0.491,
  mean: 0.76,
  stdDev: 0.6940034221817643,
  sample_size: 8 }

jsonschema: valid document, 400 times { max: 224.818,
  median: 194.503,
  min: 183.965,
  mean: 198.83875,
  stdDev: 14.102769335754596,
  sample_size: 8 }

JSV: valid document, 400 times { max: 5778.058,
  median: 5707.239,
  min: 5664.46,
  mean: 5713.368375,
  stdDev: 38.30406714024464,
  sample_size: 8 }

I find it difficult to believe JSV is actually that slow, so it's probably my fault. Possibly incorrect usage of JSV.



  • Boolean validation.
  • Correct coverage of most of Draft 3
  • benchmarking schemas of varying levels of complexity


  • validation error reports
  • complete support for "format"
  • adding more comprehensive tests to the official test suite
  • support remote references


  • Support Draft 4
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