variety

A tiny JavaScript library for working with random values

installation

yarn add variety

usage

import { sampleWeighted } from 'variety';
 
const items = [['a', 1], ['b', 5]];
 
const choice = sampleWeighted(
  items,
  myRng // optional prng function, defaults to Math.random
);
 
console.log(choice); // 'a' | 'b', five times as likely to be 'b'

api

All functions listed below optionally take a pseudorandom number generator of type PRNG as their last argument (defaults to Math.random)

rand(min = 0, max = 1): number

Returns a pseudorandom float between min (inclusive) and max (exclusive)

randInt(max: number): number

randInt(min: number, max: number): number

Returns a pseudorandom float between min (inclusive) and max (exclusive). If only one number is provided, returns a number between 0 (inclusive) and max (exclusive)

sample<T>(items: ArrayLike<T>): T

Returns a (pseudo)randomly sampled element from the given list

sampleWeighted<T>(items: [T, number][]): T

sampleWeighted<T>(items: Map<T, number>): T

Returns a weighted pseudorandom sample from either a list of [item, weight] tuples, or a Map object with item => weight key value pairs. Weights are relative to all other weights in the collection, and don't need to be normalized.

shuffle<T>(coll: T[]): T[]

Returns a shuffled (pseudorandomly sorted) permutation of coll. Does not modify coll.