Json-stringify-deterministic NPM

json-stringify-deterministic

Last version

Deterministic version of JSON.stringify(), so you can get a consistent hash from stringified results.

No Dependencies. Minimal as possible.
Better cycles detection.
Support serialization for object without .toJSON (such as RegExp).
Provides built-in TypeScript declarations.

Install

npm install json-stringify-deterministic --save

Usage

const stringify = require('json-stringify-deterministic')
const obj = { c: 8, b: [{ z: 6, y: 5, x: 4 }, 7], a: 3 }

console.log(stringify(obj))
// => {"a":3,"b":[{"x":4,"y":5,"z":6},7],"c":8}

API

stringify(<obj>, opts)

obj

Required Type: object

The input object to be serialized.

opts

opts.stringify

Type: function Default: JSON.stringify

Determinate how to stringify primitives values.

opts.cycles

Type: boolean Default: false

Determinate how to resolve cycles.

Under true, when a cycle is detected, [Circular] will be inserted in the node.

opts.compare

Type: function

Custom comparison function for object keys.

Your function opts.compare is called with these parameters:

opts.cmp({ key: akey, value: avalue }, { key: bkey, value: bvalue })

For example, to sort on the object key names in reverse order you could write:

const stringify = require('json-stringify-deterministic')

const obj = { c: 8, b: [{z: 6,y: 5,x: 4}, 7], a: 3 }
const objSerializer = stringify(obj, function (a, b) {
  return a.key < b.key ? 1 : -1
})

console.log(objSerializer)
// => {"c":8,"b":[{"z":6,"y":5,"x":4},7],"a":3}

Or if you wanted to sort on the object values in reverse order, you could write:

const stringify = require('json-stringify-deterministic')

const obj = { d: 6, c: 5, b: [{ z: 3, y: 2, x: 1 }, 9], a: 10 }
const objtSerializer = stringify(obj, function (a, b) {
  return a.value < b.value ? 1 : -1
})

console.log(objtSerializer)
// => {"d":6,"c":5,"b":[{"z":3,"y":2,"x":1},9],"a":10}

opts.space

Type: string Default: ''

If you specify opts.space, it will indent the output for pretty-printing.

Valid values are strings (e.g. {space: \t}). For example:

const stringify = require('json-stringify-deterministic')

const obj = { b: 1, a: { foo: 'bar', and: [1, 2, 3] } }
const objSerializer = stringify(obj, { space: '  ' })
console.log(objSerializer)
// => {
//   "a": {
//     "and": [
//       1,
//       2,
//       3
//     ],
//     "foo": "bar"
//   },
//   "b": 1
// }