@brillout/json-s NPM

JSON-S

JSON-Serializer

Same as JSON but with added support for:

Date
undefined
Set
Map
BigInt
RegExp
NaN
Infinity

JSON is a good serializer for JavaScript values but is lacking some JavaScript types such as Date:

const assert = require('assert')

let obj = {
  time: new Date('2042-01-01')
}

// JSON converts dates to strings
assert(obj.time.constructor === Date)
obj = JSON.parse(JSON.stringify(obj))
assert(obj.time.constructor === String)
assert(obj.time === '2042-01-01T00:00:00.000Z')

Whereas with JSON-S:

const assert = require('assert')
const { parse } = require('@brillout/json-s/parse')
const { stringify } = require('@brillout/json-s/stringify')

let obj = {
  time: new Date('2042-01-01')
}

// JSON-S preserves Date
assert(obj.time.constructor === Date)
obj = parse(stringify(obj))
assert(obj.time.constructor === Date)
assert(obj.time.getTime() === new Date('2042-01-01').getTime())

Usage

// npm install @brillout/json-s
const { parse } = require('@brillout/json-s/parse')
const { stringify } = require('@brillout/json-s/stringify')

const obj = {
  hello: 'from the future',
  time: new Date('2042-01-01')
}

// Serialize with JSON-S
const obj_serialized = stringify(obj)

// Deserialize a JSON-S string
const obj_deserialized = parse(obj_serialized)

Full Example

Example exposing all differences between JSON and JSON-S.

// /examples/json-s.js

const assert = require('assert')

const { parse } = require('@brillout/json-s/parse')
const { stringify } = require('@brillout/json-s/stringify')

const obj = {
  date: new Date(),
  undefined: undefined,
  NaN: NaN,
  Infinity: Infinity,
  regexp: /^\d+$/g
}

// All of `obj` can be serialized with JSON-S
const obj2 = parse(stringify(obj))
assert(obj2.date.getTime() === obj.date.getTime())
assert(obj2.undefined === undefined && 'undefined' in obj2)
assert(isNaN(obj2.NaN))
assert(obj2.Infinity === Infinity)
assert(obj2.regexp.toString() === obj.regexp.toString())

// JSON cannot serialize any of `obj`
const obj3 = JSON.parse(JSON.stringify(obj))
// JSON converts dates to strings
assert(obj3.constructor !== Date)
// JSON removes properties with a value of `undefined`
assert(!('undefined' in obj3))
// JSON converts `NaN` to `null`
assert(obj3.NaN === null)
// JSON converts `Infinity` to `null`
assert(obj3.Infinity === null)
// JSON converts RegExp to an empty object
assert(obj3.regexp.constructor === Object && Object.keys(obj3.regexp).length === 0)

To run the example:

$ git clone git@github.com:brillout/json-s
$ cd json-s
$ npm install
$ npm run self-link
$ node ./examples/json-s.js

The npm run self-link is required to be able to self require('@brillout/json-s').

How it Works

Let's see how JSON-S serializes an object:

// /examples/inspect.js

const { stringify } = require('@brillout/json-s/stringify')

const obj = {
  date: new Date(),
  undefined: undefined,
  collision: '!undefined',
  NaN: NaN,
  Infinity: Infinity,
  regexp: /^\d+$/g
}

console.log(stringify(obj, undefined, 2))
// Prints:
/*
{
  "date": "!Date:2021-01-12T22:15:56.319Z",
  "undefined": "!undefined",
  "collision": "!!undefined"
  "NaN": "!NaN",
  "Infinity": "!Infinity",
  "regexp": "!RegExp:/^\\d+$/g"
}
*/

JSON-S is based on JSON while using prefixed strings for unsupported types.

JSON-S uses the native JSON.parse and JSON.stringify functions while modifying the serialization of unsupported types.