@jdw/jst

JST - JSON Schema Toolkit
===

> A library for working with json schema.

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.

Quick-start

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';
`

API

$3

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

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

#### Usage

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

const data = {
foo: 99
};

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

$3

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

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

#### Usage

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

const data = {
foo: 99
};

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

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

#### isPointer

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

* isPointer(subject: string) => boolean

#### Usage

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

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

$3

Dereferences a schema according to the json references specification.

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

#### Usage

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.

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

const schema = {
'car': {
'#/def/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
});
`

Contributing

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

$3

- NodeJS >= 6

$3

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.