BookOwl / browser-alea

A simple copy-and-paste implementation of Johannes Baagøe's Alea PRNG modified to work in the browser

Alea

A simple copy-and-paste implementation of Johannes Baagøe's Alea PRNG modified to work in the browser.

Mostly packaged so I can easily include it in my projeccts. Nothing more

JavaScript's Math.random() is fast, but has problems. First, it isn't seedable, second, its randomness leaves a bit to be desired. Johannes Baagøe has done some great work in trying to find a more modern PRNG algorithm that performs well on JavaScript, and Alea seems to be the one that has come out ahead (benchmarks).

Installation

Link to alea.js in your html file.

Usage

var prng = new Alea() // add an optional seed param

var nextRandnum = prng() // just call the return value of Alea

Additions

Also adds the ability to sync up two Alea PRNGs via the importState and exportState methods.

var prng1 = new Alea(200)

prng1()
prng1()

// after generating a few random numbers, we will initialize a new PRNG

var prng2 = Alea.importState(prng1.exportState())

// this should echo true, true, true
console.log(prng2() == prng1())
console.log(prng2() == prng1())
console.log(prng2() == prng1())

The theory behind this is that while a server is running a simulation (for example, a game) and clients connect to the server, each client will run its own simulation without having to depend 100% on the server for every update of the simulation state. By importing the current generator state from the server, a client can join in at any time and have an accurate simulation fully in sync with the server.

Acknowledgements

Everything in this module was made by Johannes Baagøe. I just wanted this in npm. Read more on his homepage.