JustMyLuck

A collection of utility functions for working with randomness.

setup

npm

npm i just-my-luck

ES module

import JustMyLuck from 'just-my-luck';

Node

let JustMyLuck = require('just-my-luck');

browser

<script src="https://unpkg.com/just-my-luck"></script>

The module is globally available as JustMyLuck.

members

static properties

.random = Math.random

.MersenneTwister(seed)

The implementation of the Mersenne Twister pseudo-random number generator.

Returns the pseudo-random number generator as a function.

let random = JustMyLuck.MersenneTwister(835);
console.log(random()); // => 0.7212939869047637
console.log(random()); // => 0.2532498844651273

.lowerCasedAlphabetic = 'abcdefghijklmnopqrstuvwxyz'

.upperCasedAlphabetic = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

.alphabetic = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'

.numeric = '0123456789'

.lowerCasedAlphanumeric = 'abcdefghijklmnopqrstuvwxyz0123456789'

.upperCasedAlphanumeric = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

.alphanumeric = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

constructor

new JustMyLuck(random)

let seed = Date.now();
let luck1 = new JustMyLuck(JustMyLuck.MersenneTwister(seed));
let luck2 = new JustMyLuck(JustMyLuck.MersenneTwister(seed));
let integer1 = luck1.integer(-2, 2, true);
let integer2 = luck2.integer(-2, 2, true);
console.log(integer1 === integer2); // => true;

instance properties

.random

The pseudo-random number generator.

static and instance methods

.boolean()

Generates a boolean.

Returns the generated boolean.

let boolean = JustMyLuck.boolean();
// => either true or false

.booleanWeighted(weight)

Generates a boolean using a weighted probability.

Returns the generated boolean.

let boolean = JustMyLuck.booleanWeighted(3);
// => either true (75%) or false (25%)

console.log(JustMyLuck.booleanWeighted(0) === false); // => true

console.log(JustMyLuck.booleanWeighted(Infinity) === true); // => true

.float(min, max, inclusive = false)

Generates a float within a range.

Returns the generated float.

let float = JustMyLuck.float(0.4, 2.7);
// => a float greater than or equal to 0.4 and less than 2.7

let float = JustMyLuck.float(0.4, 2.7, true);
// => a float greater than or equal to 0.4 and less than or equal to 2.7

let float = 6.5;
console.log(JustMyLuck.float(float, float, true) === float); // => true

.integer(min, max, inclusive = false)

Generates an integer within a range.

Returns the generated integer.

let integer = JustMyLuck.integer(2, 11);
// => an integer greater than or equal to 2 and less than 11

let integer = JustMyLuck.integer(2, 11, true);
// => an integer greater than or equal to 2 and less than or equal to 11

console.log(JustMyLuck.integer(4.3, 6.5) === 5); // => true

.string(alphabet, length)

Generates a string using an alphabet.

Returns the generated string.

let string = JustMyLuck.string(JustMyLuck.alphabetic, JustMyLuck.integer(8, 16, true));
// => 'eFEgkjWzTsTmA'

.date(min, max, inclusive = false)

Generates a Date instance within a range.

Returns the generated Date instance.

let date = JustMyLuck.date(new Date('01 Jan 1970'), new Date('04 Dec 1995'));
// => '1989-08-26T01:02:17.622Z'

let date = new Date('04 Dec 1995');
console.log(JustMyLuck.date(date, date, true).getTime() === date.getTime()); // => true

.single(collection)

Selects a value from a collection.

Returns the selected value.

let value = JustMyLuck.single(['a', 'b', 'c']);
// => either 'a', 'b' or 'c'

.singleWeighted(weightedCollection)

Selects a value from a collection using a weighted probability.

Returns the selected value.

let value = JustMyLuck.singleWeighted([['a', 3.3], ['b', 0.7], ['c', 1]]);
// => either 'a' (66%), 'b' (14%) or 'c' (20%)

.combination(collection, maxCount)

Selects a combination of values without repetition from a collection. Preserves the order of the values.

Returns the selected values as an array.

let values = JustMyLuck.combination(['a', 'b', 'c', 'd', 'e'], 3);
// => ['a', 'b', 'd']

.combinationWeighted(weightedCollection, maxCount)

Selects a combination of values without repetition from a collection using a weighted probability. Preserves the order of the values.

Returns the selected values as an array.

let values = JustMyLuck.combinationWeighted([['a', 2], ['b', 7], ['c', 8], ['d', 5], ['e', 8]], 3);
// => ['a', 'c', 'e']

.permutation(collection, maxCount)

Selects a permutation of values without repetition from a collection.

Returns the selected values as an array.

let values = JustMyLuck.permutation(['a', 'b', 'c', 'd', 'e'], 3);
// => ['b', 'd', 'a']

.permutationWeighted(weightedCollection, maxCount)

Selects a permutation of values without repetition from a collection using a weighted probability.

Returns the selected values as an array.

let values = JustMyLuck.permutationWeighted([['a', 2], ['b', 7], ['c', 8], ['d', 5], ['e', 8]], 3);
// => ['c', 'e', 'a']

.multicombination(collection, count)

Selects a combination of values with repetition from a collection. Preserves the order of the values.

Returns the selected values as an array.

let values = JustMyLuck.multicombination(['a', 'b'], 8);
// => ['a', 'a', 'a', 'a', 'a', 'b', 'b', 'b']

.multicombinationWeighted(weightedCollection, count)

Selects a combination of values with repetition from a collection using a weighted probability. Preserves the order of the values.

Returns the selected values as an array.

let values = JustMyLuck.multicombinationWeighted([['a', 1], ['b', 3]], 8);
// => ['a', 'b', 'b', 'b', 'b', 'b', 'b', 'b']

.multipermutation(collection, count)

Selects a permutation of values with repetition from a collection.

Returns the selected values as an array.

let values = JustMyLuck.multipermutation(['a', 'b'], 8);
// => ['a', 'a', 'b', 'b', 'a', 'a', 'b', 'a']

.multipermutationWeighted(weightedCollection, count)

Selects a permutation of values with repetition from a collection using a weighted probability.

Returns the selected values as an array.

let values = JustMyLuck.multipermutationWeighted([['a', 1], ['b', 3]], 8);
// => ['b', 'b', 'b', 'a', 'b', 'b', 'b', 'b']

.shuffle(collection)

Shuffles a collection.

Returns the shuffled collection as an array.

let shuffledArray = JustMyLuck.shuffle([1, 2, 3, 4, 5]);
// => [4, 3, 2, 5, 1]

.shuffleInPlace(array)

Shuffles an array in place.

Returns the same array but shuffled.

plugins

Write your own plugins to extend the library.

import JustMyLuck from 'just-my-luck';

JustMyLuck.extend({
  color() {
    return `rgb(${[0, 0, 0].map(() => this.integer(0, 255, true)).join(',')})`;
  },
});