stable-hash-x



A tiny and fast (600B ^unpkg) lib for "stably hashing" a JavaScript value, works with cross-realm objects. Originally created for SWR by [Shu Ding][] at stable-hash, we forked it because the original one is a bit out of maintenance for a long time.

It's similar to JSON.stringify(value), but:

1. Supports any JavaScript value (BigInt, NaN, Symbol, function, class, ...)
2. Sorts object keys (stable)
3. Supports circular objects

TOC

- Use
- Examples
- Primitive Value
- Regex
- Date
- Array
- Object
- Function, Class, Set, Map, Buffer...
- Cross-realm
- Benchmark
- Notes
- Sponsors and Backers
- Sponsors
- Backers
- Changelog
- License

Use

``bash
yarn add stable-hash-x
`

`js
import { hash } from 'stable-hash-x'

hash(anyJavaScriptValueHere) // returns a string

hash(anyJavaScriptValueHere, true) // if you're running in cross-realm environment, it's disabled by default for performance
`

Examples

$3

`js
hash(1)
hash('foo')
hash(true)
hash(undefined)
hash(null)
hash(NaN)
`

BigInt:

`js
hash(1) === hash(1n)
hash(1) !== hash(2n)
`

Symbol:

`js
hash(Symbol.for('foo')) === hash(Symbol.for('foo'))
hash(Symbol.for('foo')) === hash(Symbol('foo'))
hash(Symbol('foo')) === hash(Symbol('foo'))
hash(Symbol('foo')) !== hash(Symbol('bar'))
`

_Since Symbols cannot be serialized, stable-hash-x simply uses its description as the hash._

$3

`js
hash(/foo/) === hash(/foo/)
hash(/foo/) !== hash(/bar/)
`

$3

`js
hash(new Date(1)) === hash(new Date(1))
`

$3

`js
hash([1, '2', [new Date(3)]]) === hash([1, '2', [new Date(3)]])
hash([1, 2]) !== hash([2, 1])
`

Circular:

`js
const foo = []
foo.push(foo)
hash(foo) === hash(foo)
`

$3

`js
hash({ foo: 'bar' }) === hash({ foo: 'bar' })
hash({ foo: { bar: 1 } }) === hash({ foo: { bar: 1 } })
`

Stable:

`js
hash({ a: 1, b: 2, c: 3 }) === hash({ c: 3, b: 2, a: 1 })
`

Circular:

`js
const foo = {}
foo.foo = foo
hash(foo) === hash(foo)
`

$3

stable-hash-x guarantees reference consistency (===) for objects that the constructor isn't Object.

`js
const foo = () => {}
hash(foo) === hash(foo)
hash(foo) !== hash(() => {})
`

`js
class Foo {}
hash(Foo) === hash(Foo)
hash(Foo) !== hash(class {})
`

`js
const foo = new Set([1])
hash(foo) === hash(foo)
hash(foo) !== hash(new Set([1]))
`

$3

`js
import { runInNewContext } from 'node:vm'

const obj1 = {
a: 1,
b: new Date('2022-06-25T01:55:27.743Z'),
c: /test/,
f: Symbol('test'),
}
const obj2 = runInNewContext(({
a: 1,
b: new Date('2022-06-25T01:55:27.743Z'),
c: /test/,
f: Symbol('test'),
}))

obj1 === obj2 // false
hash(obj1) === hash(obj2, true) // true
`

Benchmark

`log
┌─────────┬────────────────────────────────┬──────────────────┬───────────────────┬────────────────────────┬────────────────────────┬─────────┐
│ (index) │ Task name │ Latency avg (ns) │ Latency med (ns) │ Throughput avg (ops/s) │ Throughput med (ops/s) │ Samples │
├─────────┼────────────────────────────────┼──────────────────┼───────────────────┼────────────────────────┼────────────────────────┼─────────┤
│ 0 │ 'stable-hash-x' │ '7877.4 ± 1.57%' │ '7042.0 ± 167.00' │ '138708 ± 0.05%' │ '142005 ± 3449' │ 126975 │
│ 1 │ 'hash-object' │ '17632 ± 0.73%' │ '16708 ± 458.00' │ '58820 ± 0.07%' │ '59852 ± 1600' │ 56716 │
│ 2 │ 'json-stringify-deterministic' │ '10901 ± 0.83%' │ '10250 ± 250.00' │ '95860 ± 0.05%' │ '97561 ± 2439' │ 91739 │
│ 3 │ 'stable-hash' │ '8318.5 ± 3.27%' │ '7042.0 ± 208.00' │ '138347 ± 0.06%' │ '142005 ± 4074' │ 120214 │
└─────────┴────────────────────────────────┴──────────────────┴───────────────────┴────────────────────────┴────────────────────────┴─────────┘
`

Notes

This function does something similar to JSON.stringify, but more than it. It doesn't generate a secure checksum, which usually has a fixed length and is hard to be reversed. With stable-hash-x it's still possible to get the original data. Also, the output might include any charaters, not just alphabets and numbers like other hash algorithms. So:

- Use another encoding layer on top of it if you want to display the output.
- Use another crypto layer on top of it if you want to have a secure and fixed length hash.

`js
import crypto from 'node:crypto'

import { hash } from 'stable-hash-x'

const weakHash = hash(anyJavaScriptValueHere)
const encodedHash = Buffer.from(weakHash).toString('base64')
const safeHash = crypto.createHash('MD5').update(weakHash).digest('hex')
``

Also, the consistency of this lib is sometimes guaranteed by the singularity of the WeakMap instance. So it might not generate the consistent results when running in different runtimes, e.g. server/client or parent/worker scenarios.

Sponsors and Backers


$3

| 1stG | RxTS | UnRS | UnTS |
| ---------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
|  |  |  |  |

$3

| 1stG | RxTS | UnRS | UnTS |
| ------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
|  |  |  |  |

Changelog

Detailed changes for each release are documented in CHANGELOG.md.

License

Originally created by [Shu Ding].

[MIT][] © [JounQin][]@[1stG.me][]

[1stG.me]: https://www.1stG.me
[MIT]: http://opensource.org/licenses/MIT
[JounQin]: https://github.com/JounQin
[Shu Ding]: https://github.com/shuding