# seeded-random-utilities

Common random functions that are seedable written in TypeScript with TypeScript support.

The `rand-seed`

npm package provides a random number generator similar to Math.random except with seeding. This package uses `rand-seed`

to provide random numbers, but also implements some common easy-to-use random utilities.

## Installation

This package is available through *npm*:

```
npm install --save seeded-random-utilities
```

## Usage

Either import directly

or import in your own scripts using

`;`

Then simply create a new instance with an (optional) seed:

`const rand = '1234'; rand; // Generate a new random number`

If no seed is specified the call to `rand.random()`

will simply be forwarded to `Math.random()`

. So it won't operate in a repeatable seeded fashion if no seed is supplied.

`// Create a new random number generator using the xoshiro128** algorithmconst rand = '1234' PRNGxoshiro128ss;`

An interface is provided for the main random class, `RandomUtilities`

.

## Example

A simple example is included. This may be run with *node*: `node sample/index.js`

Another example that was used to verify that the package can be installed and used properly can be found in `sample/test-random-unique-integers-lists`

. A test package is in there that one can use to examine large sets of the output from `generateRandomArrayOfUniqueIntegers`

.

## API

Method | Description |
---|---|

random(): number, getRandom(): number | Generate a random integer. |

getRandomIntegar(max: number, min = zero): number | Generate a random integer. |

getRandomArbitrary(max: number, min = zero): number | Generate a random arbitary. |

getRandomIntInclusive(max: number, min = zero): number | Generate a random max inclusive integer. |

getRandomBool(): boolean | Generate a random boolean (true/false). |

getRandomChar(): string | Generate a random character. |

selectRandomElement(source: T[]): T | |

selectUniqueRandomElements(source: T[], picks: number): T[] | Select a number of random unique elments in a provided array |

shuffle(array: T[], copy?: boolean): T[] | string |

chooseBooleanRandomlyWithProbability(itemCount: number, picks?: number): boolean | Choose a number of boolean randomly with the provide percentage |

generateRandomArrayOfUniqueIntegers(amount: number, maxValue: number): number[] | Choose a list of unique integers out of a list of consecutive integers |

## Contributing

Pull requests and stars are highly welcome.

For bugs and feature requests, please create an issue.

## Motivations

In a recent project I was working on I needed the use of a seeded random number generator, preferably written in TypeScript. I found rand-seed, but while it provided the basic engine to run randomization it didn't have any implementation for picking unique numbers out of a set or really anything other than the root output similar to Math.random(). I had been waiting for an excuse to make a TypeScript style npm package, in order to provide tangible proof of my understanding of TypeScript. So this seemed like the perfect excuse to attempt to fill a narrow niche with a package that had a set of random utilities as well as one that was seeded and in TypeScript. I started reading different TypeScript npm package tutorials and finally settled on using How to Create and Publish an NPM module in TypeScript I first attemptted implementing simple utilities like generating a random integer. For and more, I kept seeing people point to the [MDN article on Math.Random], and noticed that it some nice basic implementations of many common random utilities. So I adapted most of those utilities to the new seeded TypeScript package I was buliding. Then I noticed the random-utility - npm, while I was getting close to have creating a unique element picking algorithm. I adapted some of the easy to adapte to seeded TypeScript versions. Finally I noticed more and more I liked the TypeScript project setup in rand-seed and ended up copying more and more of it i into my project. It gave me chance to work on rollup which I hadn't gotten into yet. Thanks to all mentioned and those unmentioned that I don't know of.

## Links

- "rand-seed - npm" - Provides the seeded random implementation powering the utilities. Also directly used a lot of the TypeScript setup and project design from here, blending it partly with the following tutorial link and other random utilities.
- "How to Create and Publish an NPM module in TypeScript" - One of the best tutorials on how to publish a TypeScript package that is usefulable in both JavaScript and TypeScript.
- "Math.random() - JavaScript | MDN" - This MDN web doc provided the inspriation and logic behind many of the utilities. They were adpated to both seeding and into TypeScript.
- "random-utility - npm" - I created seeded versions of a few of these utitlities. It wasn't a straight rip, more just inspiration.