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# node-object-hash
Tiny and fast node.js object hash library with properties/arrays sorting to provide constant hashes.
It also provides a method that returns sorted object strings that can be used for object comparison without hashes.
One of the fastest among other analogues (see [benchmarks](#benchmarks)).
Hashes are built on top of node's crypto module
(so for using in browser use something like [browserify-crypto](https://github.com/crypto-browserify/crypto-browserify) or some kind of crypto functions polyfills). Or you can use only `objectSorter` ([source](https://github.com/SkeLLLa/node-object-hash/blob/master/objectSorter.js)) for getting your objects' string representation and compare or pass them to your own hash function.
[](https://nodejs.org/download/release/latest)[](https://npmjs.org/package/node-object-hash)[](https://npmjs.org/package/node-object-hash)[](https://npms.io/search?q=node-object-hash)[](https://travis-ci.org/SkeLLLa/node-object-hash)[](https://snyk.io/test/github/skellla/node-object-hash)[](https://codeclimate.com/github/SkeLLLa/node-object-hash/test_coverage)[](https://codeclimate.com/github/SkeLLLa/node-object-hash/maintainability)[](http://inch-ci.org/github/SkeLLLa/node-object-hash)[](https://github.com/igrigorik/ga-beacon)
# Installation
`npm i node-object-hash -S`
# Features
- Supports object property sorting for constant hashes for objects with same properties, but different order.
- Supports ES6 Maps and Sets.
- Supports type coercion (see table below)
- Supports all hashes and encodings of crypto library
- Supports large objects and arrays
- Very fast comparing to other libs (see [Benchmarks](#benchmarks) section)
## Type map
This map displays what types will have identical string representation (e.g. new Set([1, 2, 3]) and [1, 2, 3] will have
equal string representations and hashes.
| Initial type | Mapped type |
|---------------------------|--------------|
| Array ([]) | array |
| ArrayObject (new Array()) | |
| Int8Array | |
| Uint8Array | |
| Uint8ClampedArray | |
| Int16Array | |
| Uint16Array | |
| Int32Array | |
| Uint32Array | |
| Float32Array | |
| Float64Array | |
| Buffer | |
| Set | |
| | |
| Map | array[array] |
| | |
| string ('') | string | string |
| String (new String()) | |
| | |
| boolean (true) | boolean |
| Boolean (new Boolean()) | |
| | |
| number (true) | number |
| Number (new Number()) | |
| | |
| Date | date |
| | |
| Symbol | symbol |
| | |
| undefined | undefined |
| | |
| null | null |
| | |
| function | function |
| | |
| Object ({}) | object |
| Object (new Object()) | |
| | |
| other | unknown |
## Coercion map
| Initial "type" | Coerced type | Example |
|----------------|----------------|--------------|
| boolean | string | true -> 1 |
| number | string | '1' -> 1 |
| string | string | 'a' -> a |
| null | string (empty) | null -> |
| undefined | string (empty) | undefined -> |
# Changes
See [changelog](CHANGELOG.md)
# API overview
## 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;
## API methods
### `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'`);
### `sort(object)`
Returns sorted string generated from object (can be used for object comparison)
* `object`:`*` - object for sorting;
# Full API docs ([separate page](API.md))
{{>main}}
# Requirements
## version \>=1.0.0
- `>=nodejs-0.10.0`
## version \>=0.1.0 && <1.0.0
- `>=nodejs-6.0.0`
- `>=nodejs-4.0.0` (requires to run node with `--harmony` flag)
## browsers
- nodejs `crypto` module for browsers (e.g. [browserify-crypto](https://github.com/crypto-browserify/crypto-browserify)).
# Example
```js
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.sort(object.c);
// returns '[0,1,2,3,4]'
```
For more examples you can see [tests file](https://github.com/SkeLLLa/node-object-hash/blob/master/test/hash2.js)
or try it out online at [runkit](https://runkit.com/skellla/node-object-hash-example)
# Benchmarks
Bench data - array of 100000 complex objects
## Usage
* `npm run bench` to run custom benchmark
* `npm run bench2` to run benchmark suite
## Results
### Custom benchmark ([code](bench/index.js))
| Library | Time (ms) | Memory (Mb) |
|---------------------------------------|------------|--------------------|
| node-object-hash-0.2.1 | 5813.575 | 34 |
| node-object-hash-1.0.X | 2805.581 | 27 |
| node-object-hash-1.1.X (node v7) | 2555.583 | 27 |
| node-object-hash-1.2.X (node v7) | 2390.752 | 28 |
| object-hash-1.1.5 (node v7) | 28115.553 | 39 |
| object-hash-1.1.4 | 534528.254 | 41 |
| object-hash-1.1.3 | ERROR | Out of heap memory |
| hash-object-0.1.7 | 9219.826 | 42 |
### Benchmark suite module ([code](bench/bench.js))
| Library (node v7) | Perf (ops/s) |
|------------------------|--------------|
| node-object-hash-0.2.1 | 540 ±1.34% |
| node-object-hash-1.1.X | 844 ±2.51% |
| node-object-hash-1.2.X | 1021 ±1.81% |
| object-hash-1.1.5 | 106 ±0.88% |
| hash-object-0.1.7 | 305 ±1.66% |
| Library (node v10) | Perf (ops/s) |
|------------------------|--------------|
| node-object-hash-0.X.X | 758 ±1.40% |
| node-object-hash-1.4.X | 1266 ±1.44% |
| object-hash-1.3.0 | 132 ±4.08% |
| hash-object-0.1.7 | 378 ±1.36% |
## Links
* [object-hash](https://www.npmjs.com/package/object-hash) - Slow, useful for browsers because it not uses node's crypto library
* [hash-object](https://www.npmjs.com/package/hash-object) - no ES6 types support
# License
ISC