Random helpers

randoms.js

/**
 * @param {number} max the upper bound of the result
 * @return {number} random number up to (but not including) max value [0, max)
 */
const randomUpTo = max => Math.floor(Math.random() * max);

/**
 * @param {number|undefined} prob if defined, probability (percent) of the outcome being true
 * @return {boolean} [true|false]
 */
const randomBoolean = (prob = 0.5) => Math.random() > prob;

/**
 * @param {Array<*>} array the input array to get a random item from
 * @return {*} a random item from the array
 */
const randomArrayItem = array => array[randomUpTo(array.length)];

/**
 * @param {number} min lower bound
 * @param {number} max upper bound
 * @return {number} a random number between lower and upper bounds [min, max)
 */
const randomBetween = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;

// public methods, ie. export them goodies!
exports.boolean = () => randomBoolean();
exports.arrayItem = array => randomArrayItem(array);
exports.upTo = max => randomUpTo(max);
exports.between = (min, max) => randomBetween(min, max);