A json schema toolkit.


1422.0.0-beta.154 years ago5 years agoMinified + gzip package size for @jdw/jst in KB


JST - JSON Schema Toolkit

A library for working with json schema. Build Status

JST is a robust and modular library for working with json schema and provides practical utilities for some of the many specifications surrounding this standard such as json references and json pointers.

For exhaustive documentation please see the project homepage homepage. For a quick overview of jst's functionality and capabilities see below.


Install JST to your project:

npm i --save @jdw/jst

Import and begin using the functions (ES6):

import { dereference, get, set, isPointer } from '@jdw/jst';



Retrieve a value from an object as referenced by a json pointer.

  • get(object: Object, pointer: String) => any


import { get } from '@jdw/jst';

const data = {
    foo: 99

get(data, '#/foo'); // 99


Sets a value on an object as referenced by a json pointer;

  • set(object: Object, pointer: String, value: any) => void


import { set } from '@jdw/jst';

const data = {
    foo: 99

set(data, '#/foo', 77);

console.log(data); // { foo: 77 }


Performs a logical test on a string to determine if it is a json pointer.

  • isPointer(subject: string) => boolean


import { isPointer } from '@jdw/jst';

console.log(isPointer('#/foo/0/blah')); // true
console.log(isPointer('#'));            // true
console.log(isPointer('some string'));  // false


Dereferences a schema according to the json references specification.

  • dereference(schema: Object)
  • dereference(schema: Object, resolve: (id) => Object)


In it's most basic form dereference takes a schema without any external references as an argument and resolves any of it's internal pointers.

import { dereference } from '@jdw/jst';

const schema = {
    'car': {
    'def': {
        'car': {
            'type': 'string',
            'enum': ['ferrari', 'mercedes', 'bmw', 'vw']

// a resolver function is not required when de-referencing schema without external
// uri references
console.log( dereference(schema) );

This dereferences to:

    'car': {
        'type': 'string',
        'enum': ['ferrari', 'mercedes', 'bmw', 'vw']

The dereference function may be injected with a schema resolver function as its second argument. The resolve function is expected to take a schema id (uri reference) as it's input and return that schema as an object literal. This allows you to flexible in how you provision your schema be it over the wire or storing it in memory. If the resolve function cannot find the schema it is expected to throw an error.

The following is an example of using an AJV instance as supplier for a resolve function.

dereference(schema, (id) => {
    return ajv.getSchema(id).schema


Contributions to JST are most welcome, here we outline how to get setup for development.


  • NodeJS >= 6


Fork and clone this project then navigate to the project directory. Open up a terminal and run the following commands and execute npm i to install the projects development dependencies, try the following scripts out to get started - you can find more in package.json.

  • npm build: build all source code and documentation
  • npm test: run all unit test.
  • npm benchmark: run the benchmark suite (requires npm build to have been run)

Make your changes and commit your code. When you are ready, send a pull request to this repository.

If you find any bugs or have a feature request, please open an issue on github!

The npm package download data comes from npm's download counts api and package details come from npms.io.