This is a javascript implementation of the ISAAC CSPRNG.

It's ~261.95% faster than the readable implementation by rubycon at tumbling, and ~231.88% faster at returning random numbers.

Due to the focus on speed ISAACJS has not been made with the intention of being readable.

I have additionally implemented ISAAC-64 using BigInt. Please for the love of god don't actually use it; it's a PoC, slow, and ridiculous.

ISAAC-64-fast uses a simulated 64-bit integer object by having a hi and lo 32-bit integer. It's 3x faster than the BigInt version. It's still too slow to be useful and I don't trust my hi/lo arithmetic.

Create an instance of ISAAC with or without a seed.

var rng = new ISAAC(); //No seed
var rng = new ISAAC(new Uint32Array(ISAAC.prototype.SIZE)); //Zero seed
var rng = new ISAAC(ISAAC.StringToUintArray("This is a test")); //Text seed

Tumble it an arbitrary amount of times

rng.Isaac(); //Tumble once

for(var i = 0; i < 5; i++) rng.Isaac(); //Tumble five times

Tada! Go get yourself some random numbers!

rng.Rand(); //Will get the next available random 32bit unsigned integer and re-tumble it if it has run out
rng.rsl[0]; //Alternatively you can access the internal result array

Tested and working in Chrome, Firefox, IE11, and Edge.

This project is licensed under the CC0 license, meaning it is effectively public domain.