README

@buff-beacon-project/rand-utils v1.0.0 • Docs

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@buff-beacon-project/rand-utils v1.0.0

Rand Utils

rand-utils is a collection of utilities for working with pre-generated random bits. This is useful for working with public randomness beacon data or any other sources of random bits.

All methods in this library are deterministic and based on the input bits.

Installation

npm install @buff-beacon-project/rand-utils

Example

import { BitReader } from '@buff-beacon-project/rand-utils'
import { randomBytes } from 'crypto'

// create some random bits
const rand = randomBytes(64)
// create a bit reader
const reader = BitReader.from(rand)

// random directions
const directions = ['up', 'down', 'left', 'right']
const randomDirections = reader.unfold((stream) =>
  directions[stream.readBits(2, false)]
)
const list = Array.from(randomDirections)
// => [ 'down', 'right', 'up', 'left', 'down', 'right', 'up', 'left', ... ]

// shuffle an array
const arr = [0, 1, 2, 3, 4, 5, 6, 7]
const shuffled = reader.shuffled(arr)
// => [ 3, 0, 7, 4, 1, 6, 2, 5 ]

Classes

Class	Description
BitReader	Helper class to read bits from an ArrayBuffer.

Functions

Function	Description
boundedRandom	Get an unbiased "random" number within the range [0, s) from a bitStream.
getShuffleSeed	Return an array fully filled with bounded random values appropriate to shuffle a list.
shuffle	Get a shuffled copy of provided array using the given shuffle seed.
shuffleSelf	Shuffle provided array in place using the given shuffle seed.
unfoldBitstream	Utility to yield results from provided function using a bitstream. Stops when bitstream runs out of usable bits.