json-stringify-deterministic

What is json-stringify-deterministic?

The json-stringify-deterministic package is a Node.js library that provides a deterministic version of JSON.stringify. It ensures that the JSON string output is consistent across different runs by sorting the object keys, which is particularly useful for caching, hashing, or comparing JSON data.

What are json-stringify-deterministic's main functionalities?

Deterministic JSON Stringification

This feature allows you to stringify a JavaScript object into a JSON string with keys sorted in a deterministic order. This ensures that the same object will always produce the same JSON string, which is useful for consistent hashing or comparison.

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

const obj = { b: 1, a: 2 };
const jsonString = stringify(obj);
console.log(jsonString); // Output: '{"a":2,"b":1}'

Other packages similar to json-stringify-deterministic

fast-json-stable-stringify

fast-json-stable-stringify is another package that provides deterministic JSON.stringify functionality by sorting object keys. It is known for its performance and is often used in environments where speed is critical. Compared to json-stringify-deterministic, it offers similar functionality but may have different performance characteristics.

json-stable-stringify

json-stable-stringify is a widely used package that also provides deterministic JSON stringification by sorting object keys. It is one of the older packages in this space and is known for its stability and reliability. Compared to json-stringify-deterministic, it serves a similar purpose but may have different API options and performance.

README

json-stringify-deterministic

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

Similar to json-stable-stringify but:

• 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
// }

opts.replacer

Type: function

The replacer parameter is a function opts.replacer(key, value) that behaves the same as the replacer from the core JSON object.

Related

• sort-keys-recursive: Sort the keys of an array/object recursively.

License

MIT © Kiko Beats.