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index.js
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'use strict';
/**
* The Normal Bias needed to create centered Random Number Generation.
* @constant {Number}
*/
const NORMAL_BIAS = 0.289;
/**
* The High end on which the random number will be adjusted for randomness.
* @constant {Number}
*/
const HIGH_ADJUSTER = 10;
/**
* The High end on which the random number will be adjusted for randomness.
* @constant {Number}
*/
const LOW_ADJUSTER = 1
/**
* Class for generation of RandomCrap.
*
* Please do not complain about these numbers not being "true" random. The point
* behind doing this isn't to have correct math, but instead to generate numbers
* that are fun. This is why the bais exists and can be adjusted. This way the
* developer can influence the result to adjust the fun.
*
* @param {Float} [biasAdjuster="NORMAL_BIAS"]
* Allows setting a high or low bias for random generation.
*/
class RandomCrap {
constructor (biasAdjuster) {
// This is used in the random number generation to allow for high or low
// biasing. This can be used in a game to adjust the fun or difficulty.
this.biasAdjuster = (typeof biasAdjuster === 'undefined') ? NORMAL_BIAS : biasAdjuster;
}
/**
* Sets the current random bias.
*
* @param {Float} [bias="NORMAL_BIAS"]
* Allows setting a high or low bias for random generation. Setting nothing
* will reset to neutral bias.
*/
setBias (bias) {
this.biasAdjuster = (typeof bias === 'undefined') ? NORMAL_BIAS : bias;
}
/**
* Returns the current bias.
*
* @return {Boolean}
*/
getBias () {
return this.biasAdjuster;
}
/**
* Gets a random element from a supplied set.
*
* @param {Array} set
* The set from which to pull a random element.
*
* @param {String} [name="__default"]
* The name of the set, if this is set then the random element will be
* removed as a possible element in future calls.
*
* @param {Boolean} [loop="false"]
* Append the original set back onto the end if the set is empty.
*/
randomFrom(set, name, loop) {
this.sets = (typeof this.sets === 'undefined') ? [] : this.sets;
name = (typeof name === 'undefined') ? '__default' : name;
loop = (typeof loop === 'undefined') ? false : true;
let fromSet = (name === '__default') ? set.concat() : ((typeof this.sets[name] === 'undefined') ? set.concat() : this.sets[name]);
if (loop && fromSet.length === 0) {
fromSet = set.concat();
}
const length = fromSet.length;
const keys = fromSet.keys();
const indexMap = [ ... fromSet.keys() ];
const indexGet = this.simpleRandomInt(0, length - 1);
const randomElement = fromSet[indexMap[indexGet]];
fromSet.splice(indexMap[indexGet], 1);
this.sets[name] = fromSet;
return randomElement;
}
simpleRandomAlphaNum(options) {
options = Object.assign({}, options || {});
const noOfDigets = (typeof options.noOfDigets === 'undefined') ? this.simpleRandomInt(7,14) : options.noOfDigets;
let notHash = '';
for (let i = 0; i < noOfDigets; i ++) {
let alphaOrNumber = this.simpleRandomInt(1,1000);
if (alphaOrNumber % 2 === 0) {
notHash += this.simpleRandomInt(0,9);
}
else {
notHash += this.simpleRandomAlpha();
}
}
return notHash;
}
/**
* Returns a random alpha character.
*
* @param {Object} options
* Optional arguments.
*
* @param {Boolean} [options.allCaps="false"]
* Only return Capitalized letters.
*
* @param {Boolean} [options.noCaps="false"]
* Never return Capitalized letters.
*
* @param {Array} [options._set="[a, b, c, ... z]"]
* Inject set, useful for testing, or localization.
*
* @return {String}
*/
simpleRandomAlpha (options) {
options = Object.assign({}, options || {});
// In order to test this, we need to be able to inject the alpha set.
const alpha = (typeof options._set === 'undefined') ? [
'a',
'b',
'c',
'd',
'e',
'f',
'g',
'h',
'i',
'j',
'k',
'l',
'm',
'n',
'o',
'p',
'q',
'r',
's',
't',
'u',
'v',
'w',
'x',
'y',
'z',
] : options._set;
const allCaps = (typeof options.allCaps === 'undefined') ? false : options.allCaps;
const noCaps = (typeof options.noCaps === 'undefined') ? false : options.noCaps;
if (allCaps && noCaps) {
return '';
}
// This line might just be being too clever, but it works and it looks more
// elegent than a bunch of if else statements.
return (allCaps) ? this.randomFrom(alpha).toUpperCase() :
(noCaps) ? this.randomFrom(alpha).toLowerCase() :
(this.randomFrom([true,false,true,false,true,false])) ? this.randomFrom(alpha).toUpperCase() : this.randomFrom(alpha);
}
/**
* Returns a simple random floating point Number.
*
* @param {Integer} wholePrecision
* The number of precision to the left of the decimal point.
*
* @param {Integer} floatPrecision
* The number of precision to the right of the decimal point.
*
* @return {Float}
*/
simpleRandomFloat (wholePrecision, floatPrecision) {
let whole = (wholePrecision > 0) ? this.simpleRandomInt(9, 1) : '0';
for (let i = 1; i < wholePrecision; i++) {
whole += '' + this.simpleRandomInt(0, 9);
}
let float = 0;
for (let i = 1; i < floatPrecision; i++) {
float += '' + this.simpleRandomInt(0, 9);
}
return Number.parseFloat(whole + '.' + float);
}
/**
* Returns a random integer from min (inclusive) to max (inclusive).
*
* @param {Integer} min
* The lowest number to return.
*
* @param {Integer} max
* The highest number to return.
*
* @return {Integer}
*/
simpleRandomInt (min, max) {
const mathRandom = Math.random();
// The likelyAdjuster is used to give a better spread to the random numbers.
const likelyAdjuster = Math.floor(mathRandom * ((HIGH_ADJUSTER + 1) - LOW_ADJUSTER)) + LOW_ADJUSTER;
let random = parseFloat('0.' + (Math.random() * mathRandom * (new Date().getTime())));
// This algorithm has no basis in math and it naturally biases low,
// therefore it will need some adjustment from time to time. This has been
// tested and with its defaults comes out to be random.
if (random < this.biasAdjuster && Math.round(mathRandom * 100) % likelyAdjuster > 0) {
random += this.biasAdjuster;
}
return Math.floor(random * ((max + 1) - min)) + min;
}
}
module.exports = RandomCrap;