esm-seedrandom

esm-seedrandom

Seeded random number generator for JavaScript, ported to ES Modules.

Unit tested for number generator compatability with original seedrandom CommonJS NPM package.

• Version: 3.0.5
• Author: David Bau
• Date: 2019-09-14
• ES Modules port in 2020-12 by Shane Holloway

Use

<script type="module">
  import {prng_alea} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/alea.min.mjs'

  let myrng = prng_alea('an example seed string')

  console.log(myrng()); // Always 0.2594452982302755
  console.log(myrng()); // Always 0.8253263409715146
  console.log(myrng()); // Always 0.42280301195569336

  // Use "quick" to get only 32 bits of randomness in a float.
  console.log(myrng.quick()); // Always 0.9045045920647681
  console.log(myrng.quick()); // Always 0.7626296668313444

  // Use "int32" to get a 32 bit (signed) integer
  console.log(myrng.int32()); // Always 1157605039
  console.log(myrng.int32()); // Always 346379077

  console.log(myrng.double()); // Always 0.9541419381134651
  console.log(myrng.double()); // Always 0.7982540860513401
</script>

Fast PRNG Algorithms

The package includes several fast PRNGs. To use Johannes Baagøe's extremely fast Alea PRNG:

// Use alea for Johannes Baagøe's clever and fast floating-point RNG.
import {prng_alea} from 'esm-seedrandom';
let arng = prng_alea('hello.');

// By default provides 32 bits of randomness in a float.
console.log(arng());               // Always 0.4783254903741181

// Use "double" to get 56 bits of randomness.
console.log(arng.double());        // Always 0.8297006866124559

// Use "int32" to get a 32 bit (signed) integer.
console.log(arng.int32());         // Always 1076136327

PRNG name	Period	Author
prng_alea	~2^116	Baagøe
prng_xor128	2^128-1	Marsaglia
prng_tychei	~2^127	Neves/Araujo (ChaCha)
prng_xorwow	2^192-2^32	Marsaglia
prng_xor4096	2^4096-2^32	Brent (xorgens)
prng_xorshift7	2^256-1	Panneton/L'ecuyer
prng_arc4	~2^1600	Bau (ARC4)

Docs

npm install esm-seedrandom

or in HTML,

<script type='module'>
  import {prng_alea} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/index.min.mjs'

  // or use the individual algorithms by module

  import {prng_alea} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/alea.min.mjs'
  import {prng_xor128} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/xor128.min.mjs'
  import {prng_tychei} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/tychei.min.mjs'
  import {prng_xorwow} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/xorwow.min.mjs'
  import {prng_xor4096} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/xor4096.min.mjs'
  import {prng_xorshift7} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/xorshift7.min.mjs'
  import {prng_arc4} from '//cdn.jsdelivr.net/npm/esm-seedrandom/esm/arc4.min.mjs'
</script>

Saving & Restoring PRNG state

import {prng_alea} from 'esm-seedrandom';

let rng_first = prng_alea("secret-seed", {state: true});
let saved_state = rng_first.state()
for (let j = 0; j < 1e5; ++j)
  rng_first();

// later

let rng_replica = prng_alea("", {state: saved_state});
for (let j = 0; j < 1e5; ++j)
  rng_replica();

In normal use the prng is opaque and its internal state cannot be accessed. However, if the "state" option is specified, the prng gets a state() method that returns a plain object the can be used to reconstruct a prng later in the same state (by passing that saved object back as the state option).

LICENSE (MIT)

Copyright 2020 Shane Holloway. (ES Module port) Copyright 2019 David Bau.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.