jsrand a.k.a. seeded-rand
A seeded pseudo-random number generator for JavaScript.
It can be used as either a plain script or as a Node.js module.
Numbers are generated using a one-seeded version of the multiply-with-carry method by George Marsaglia. While this method is okay for most applications, it is not cryptographically strong.
jsrand supports saving and restoring the generator state and common operations on arrays: choice (pick a random element), choices (pick elements at random), sample (pick elements at random without repetition) and shuffle.
Table of contents
Install
NPM
$ npm install seeded-rand
Plain script
Just download dist/jsrand.min.js and (optionally) dist/jsrand.min.js.map and include it in your app.
Usage
| Plain script | NPM |
|---|---|
<script src="jsrand.min.js"></script>This will define a global |
const Srand = require('seeded-rand');or import Srand from 'seeded-rand'; |
All methods can be used either statically:
Srand.seed(10); // 10
Srand.random(); // 0.4569510892033577or instantiating a new generator:
const rnd = new Srand(10);
rnd.random(); // 0.4569510892033577
const othr = new Srand(rnd.seed());
othr.random(); // 0.4569510892033577Examples
const rnd = new Srand(); // Initiate with random seed
rnd.seed(); // 1836504610 Read the seed
rnd.randomize(); // 3409024789 Random seed is set and returned
rnd.seed(1836504610); // 1836504610 Set a seed
rnd.inRange(0, 10); // 6.866552880965173
rnd.intInRange(0, 10); // 1
rnd.choice([1, 2, 3]); // 3
rnd.choices([1, 2, 3], 3); // [3, 3, 1] possible repetitions
rnd.choices([1, 2, 3], 3); // [2, 2, 3] possible repetitions
rnd.sample([1, 2, 3], 2); // [1, 2] no repetitions
rnd.sample([1, 2, 3], 2); // [1, 2] no repetitions
const state = rnd.getState();
rnd.intInRange(1, 50); // 39
rnd.intInRange(1, 50); // 24
rnd.intInRange(1, 50); // 18
rnd.setState(state); // Resumes previous state, regenerating same random sequence
rnd.intInRange(1, 50); // 39
rnd.intInRange(1, 50); // 24
rnd.intInRange(1, 50); // 18The same sequence of operations can be repeated with equal results using the static methods of Srand:
Srand.seed(1836504610); // 1836504610 Set the seed
Srand.inRange(0, 10); // 6.866552880965173
Srand.intInRange(0, 10); // 1
Srand.choice([1, 2, 3]); // 3
Srand.choices([1, 2, 3], 3); // [3, 3, 1] possible repetitions
Srand.choices([1, 2, 3], 3); // [2, 2, 3] possible repetitions
Srand.sample([1, 2, 3], 2); // [1, 2] no repetitions
Srand.sample([1, 2, 3], 2); // [1, 2] no repetitions
const state = Srand.getState();
Srand.intInRange(1, 50); // 39
Srand.intInRange(1, 50); // 24
Srand.intInRange(1, 50); // 18
Srand.setState(state); // Resumes previous state, regenerating same random sequence
Srand.intInRange(1, 50); // 39
Srand.intInRange(1, 50); // 24
Srand.intInRange(1, 50); // 18API
| Method | Doc |
|---|---|
choice(arr: Array<T>): T |
Returns a random element from If |
choices(arr: Array<T>, k: number): Array<T> |
Returns a If For an alternative without replacement, see |
getState(): State |
Returns an object with the state of the generator.
Use |
inRange(a: number, b: number): number |
Returns a pseudo-random float number between |
intInRange(min: number, max: number): number |
Returns a psuedo-random integer between |
noConflict(): Srand |
Only available when using Srand as a plain script. In the uncommon case the name Srand = "my value";
// .. jsrand is loaded ...
const mySrand = Srand.noConflict();
Srand; // "my value" |
random(): number |
Returns a pseudo-random float number between 0 inclusive and 1 exclusive. The algorithm used is a one-seeded version of the multiply-with-carry method by George Marsaglia. |
randomize(): number |
Sets and returns a random seed. |
sample(arr: Array<T>, k: number): Array<T> |
Returns a If For an alternative with replacement, see |
seed(seed?: number): number |
Sets or gets (if no argument is given) the seed.
The seed can be any float or integer number. |
setState(state: State): void |
Resume a state previously returned by |
shuffle(arr: Array<T>): Array<T> |
Shuffles |
License
Copyright © 2014-2020, Domenico De Felice.
Provided under the terms of the MIT License.