esm-seedrandom

Explicitly 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

Demo

GitHub Pages-based Live demo

Use

Fast PRNG Algorithms

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 myrng = prng_alea('hello.');

// By default provides 32 bits of randomness in a float.
console.log(myrng());               // Always 0.4783254903741181 for this seed and sequence
console.log(myrng.quick());         // Always 0.8297006865032017 for this seed and sequence

// Use "double" to get 56 bits of randomness.
console.log(myrng.double());        // Always 0.4692433053279662 for this seed and sequence

// Use "int32" to get a 32 bit (signed) integer.
console.log(myrng.int32());         // Always 1350551666 for this seed and sequence

or direclty from HTML,

Docs

See the API docs.

Overview

From NodeJS,

npm install esm-seedrandom

or in HTML,

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 provided, 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).

Unit tests

Mocha-based live unittests for reproducability and validation of state capture and restore.

In NodeJS unittests, validation of state snapshot compatability with the original seedrandom CommonJS implementation is performed.

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.