node-object-hash

What is node-object-hash?

The node-object-hash package is a utility for creating consistent hash values from JavaScript objects. It is useful for tasks such as caching, object comparison, and ensuring data integrity.

What are node-object-hash's main functionalities?

Hashing Objects

This feature allows you to create a hash from a JavaScript object. The hash can be used to uniquely identify the object.

const objectHash = require('node-object-hash');
const hasher = objectHash();
const obj = { name: 'John', age: 30 };
const hash = hasher.hash(obj);
console.log(hash);

Custom Hashing Options

This feature allows you to customize the hashing process by specifying options such as coercion and the hashing algorithm.

const objectHash = require('node-object-hash');
const hasher = objectHash({ coerce: true, alg: 'sha256' });
const obj = { name: 'John', age: 30 };
const hash = hasher.hash(obj);
console.log(hash);

Hashing Arrays

This feature allows you to create a hash from an array, ensuring that the array's contents are uniquely identified.

const objectHash = require('node-object-hash');
const hasher = objectHash();
const arr = [1, 2, 3, 4];
const hash = hasher.hash(arr);
console.log(hash);

Other packages similar to node-object-hash

object-hash

The object-hash package is another utility for creating hash values from JavaScript objects. It offers similar functionality to node-object-hash but with a different API and additional features such as support for circular references.

hash-it

The hash-it package provides a simple and fast way to hash JavaScript objects. It is designed to be lightweight and easy to use, making it a good alternative to node-object-hash for basic hashing needs.

crypto

The built-in crypto module in Node.js can also be used to create hash values from objects. While it requires more manual setup compared to node-object-hash, it offers greater flexibility and is part of the standard library.

README

node-object-hash

Node.js object hash library with properties/arrays sorting to provide constant hashes.

Built on top of node's crypto module (so for using in browser use something like browserify or use crypto functions polyfills).

Installation

npm i node-object-hash

Features

• Supports object property sorting for constant hashes for objects with same properties, but different order.
• Supports ES6 Maps and Sets.
• Supports type coercion (e.g. 1 and "1" will be the same)
  • rules:
    • numbers and strings represented without quotes;
    • boolean values converted to numbers;
• Supports all hashes and encodings of crypto library
• Supports large objects and arrays

Changes

v0.x.x -> v1.0.0

• Sorting mechanism rewritten form ES6 Maps to simple arrays (add <=node-4.0.0 support)
• Performance optimization (~2 times faster than 0.x.x)
• API changes:
  • Now module returns 'constructor' function, where you can set default parameters: var objectHash = require('node-object-hash')(options);

API

Constructor require('node-object-hash')([options])

Returns preconfigured object with API

Parameters:

• options:<object> - object with hasher config options
• options.coerce:<boolean> - if true performs type coercion (default: true); e.g. hash(true) == hash('1') == hash(1), hash(false) == hash('0') == hash(0)
• options.sort:<boolean> - if true performs sorting on objects, arrays, etc. (default: true);
• options.alg:<string> - sets default hash algorithm (default: 'sha256'); can be overridden in hash method;
• options.enc:<string> - sets default hash encoding (default: 'hex'); can be overridden in hash method;

hash(object[, options])

Returns hash string.

• object:<*> object for calculating hash;
• options:<object> object with options;
• options.alg:<string> - hash algorithm (default: 'sha256');
• options.enc:<string> - hash encoding (default: 'hex');

sortObject(object)

Returns sorted string generated from object

• object:<*> - object for sorting;

Requirements

• >=nodejs-0.10.0 (starting from version 1.0.0)
• >=nodejs-6.0.0
• >=nodejs-4.0.0 (requires to run node with --harmony flag)
• nodejs crypto module

Example

var hasher = require('node-object-hash');

var hashSortCoerce = hasher({sort:true, coerce:true});
// or
// var hashSortCoerce = hasher();
// or
// var hashSort = hasher({sort:true, coerce:false});
// or
// var hashCoerce = hasher({sort:false, coerce:true});

var objects = {
    a: {
      a: [{c: 2, a: 1, b: {a: 3, c: 2, b: 0}}],
      b: [1, 'a', {}, null],
    },
    b: {
      b: ['a', 1, {}, undefined],
      a: [{c: '2', b: {b: false, c: 2, a: '3'}, a: true}]
    },
    c: ['4', true, 0, 2, 3]
};

hashSortCoerce.hash(objects.a) === hashSortCoerce.hash(objects.b);
// returns true

hashSortCoerce.sortObject(object.c)
// returns '[0,1,2,3,4]'

Benchmark results

Bench data - array of 100000 complex objects

Usage

npm run bench

Results

	node-object-hash-0.2.1	node-object-hash-1.0.0	object-hash-1.1.4
Time	5773.869ms	2961.812ms	534528.254ms
Memory	~35Mb	~33Mb	~41Mb

Similar libraries

• https://www.npmjs.com/package/object-hash

License

ISC