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Author: SleeplessByte

concepts/randomness/.meta/config.json

@@ -1,5 +1,5 @@
 {
   "blurb": "Random number generation using Math.random()",
   "authors": ["SneakyMallard"],
-  "contributors":[]
+  "contributors": ["SleeplessByte"]
 }

concepts/randomness/about.md

@@ -1,6 +1,6 @@
 # Introduction
 
-Many programs need (apparently) random values to simulate real-world events.
+Many programs need (pseudo-)random values to simulate real-world events.
 
 Common, familiar examples include:
 
@@ -9,7 +9,25 @@ Common, familiar examples include:
 - Shuffling a deck of cards: a random ordering of a card list.
 - The creation of trees and bushes in a 3-D graphics simulation.
 
-Generating truly random values with a computer is a [surprisingly difficult technical challenge][why-randomness-is-hard], so you may see these results referred to as "pseudorandom".
+Generating truly random values with a computer is a [surprisingly difficult technical challenge][why-randomness-is-hard], which is why there are also "pseudorandom" generators.
+
+<!-- prettier-ignore -->
+~~~exercism/advanced
+[The language specification][spec] for JavaScript doesn't force the implementation for random number generation.
+All major browsers and JavaScript runtimes implement a PRNG (pseudo-random number generator).
+Because the numbers are not cryptographically secure, they should never be used for anything that requires true or at least cryptographically secure random numbers, such as certificate or password generation or operations.
+
+There is a standard called [Web Cryptography][rfc] which standardizes an interface for doing cryptography in JavaScript.
+It is implemented [by Browsers][crypto-web] as well as runtimes such as [Node.JS][crypto-node] and [Deno][crypto-deno].
+
+This concept is not about Web Crypto and will restrict itself to pseudo-random number generation.
+
+[rfc]: https://www.w3.org/TR/webcrypto-2/
+[spec]: https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-math.random
+[crypto-web]: https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
+[crypto-node]: https://nodejs.org/api/webcrypto.html#cryptogetrandomvaluestypedarray
+[crypto-deno]: https://docs.deno.com/api/web/~/Crypto
+~~~
 
 ## Generating random numbers
 
@@ -26,16 +44,18 @@ getRandomInRange(4, 10);
 // => 5.72
 ```
 
+<!-- prettier-ignore -->
+~~~exercism/advanced
+Most simple techniques of returning a range of numbers based on the randomly generated number [will introduce bias][bias].
+That means that some numbers will be more likely to be rolled than others.
+Using the multiplication technique spreads out the bias over the entire range, so it will be less obvious and in most cases not a big issue, but you should be aware of this.
+
+[bias]: https://adammil.net/blog/v134_Efficiently_generating_random_numbers_without_bias.html
+~~~
 ## Generating random integers
 
 To generate a random integer, you can use `Math.floor()` or `Math.ceil()` to turn a randomly generated number into an integer.
 
-```exercism/caution
-
-The `Math.random()` function should NOT be used for security and cryptographic applications!!
-
-Instead, you can use the Web Crypto API, which provides various cryptographic functions.
-```
 
 [why-randomness-is-hard]: https://www.malwarebytes.com/blog/news/2013/09/in-computers-are-random-numbers-really-random
 [Math.random]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random

concepts/randomness/introduction.md

@@ -1,6 +1,6 @@
 # Introduction
 
-Many programs need (apparently) random values to simulate real-world events.
+Many programs need (pseudo-)random values to simulate real-world events.
 
 Common, familiar examples include:
 
@@ -9,7 +9,13 @@ Common, familiar examples include:
 - Shuffling a deck of cards: a random ordering of a card list.
 - The creation of trees and bushes in a 3-D graphics simulation.
 
-Generating truly random values with a computer is a [surprisingly difficult technical challenge][why-randomness-is-hard], so you may see these results referred to as "pseudorandom".
+Generating truly random values with a computer is a [surprisingly difficult technical challenge][why-randomness-is-hard], which is why there are also "pseudorandom" generators.
+
+<!-- prettier-ignore -->
+~~~exercism/caution
+The `Math.random()` function should NOT be used for security and cryptographic applications!
+Finish the learning exercise(s) about this concept to learn more
+~~~
 
 ## Generating random numbers
 
@@ -30,12 +36,6 @@ getRandomInRange(4, 10);
 
 To generate a random integer, you can use `Math.floor()` or `Math.ceil()` to turn a randomly generated number into an integer.
 
-```exercism/caution
-
-The `Math.random()` function should NOT be used for security and cryptographic applications!!
-
-Instead, you can use the Web Crypto API, which provides various cryptographic functions.
-```
 
 [why-randomness-is-hard]: https://www.malwarebytes.com/blog/news/2013/09/in-computers-are-random-numbers-really-random
 [Math.random]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random

exercises/concept/captains-log/.docs/instructions.md

@@ -14,7 +14,7 @@ When it rendezvous with another starship, Mary needs to log the registry number
 
 Registry numbers start with the prefix "NCC-" and then use a number from 1000 to 9999 (both inclusive).
 
-Implement the randomShipRegistryNumber() function that returns a random starship registry number.
+Implement the `randomShipRegistryNumber()` function that returns a random starship registry number.
 
 ```javascript
 randomShipRegistryNumber();
@@ -29,7 +29,7 @@ A stardate is a floating point number.
 The adventures of the Starship Enterprise from the first season of The Next Generation take place between the stardates 41000.0 and 42000.0.
 The "4" stands for the 24th century, the "1" for the first season.
 
-Implement the function randomStardate that returns a floating point number between 41000.0 (inclusive) and 42000.0 (exclusive).
+Implement the function `randomStardate` that returns a floating point number between 41000.0 (inclusive) and 42000.0 (exclusive).
 
 ```javascript
 randomStardate();
@@ -43,7 +43,7 @@ Planets in the Star Trek universe are split into categories based on their prope
 For example, Earth is a class M planet.
 All possible planetary classes are: D, H, J, K, L, M, N, R, T, and Y.
 
-Implement the randomPlanetClassfunction.
+Implement the `randomPlanetClass()` function.
 It should return one of the planetary classes at random.
 
 ```javascript

exercises/concept/captains-log/.docs/introduction.md

@@ -1,6 +1,6 @@
 # Introduction
 
-Many programs need (apparently) random values to simulate real-world events.
+Many programs need (pseudo-)random values to simulate real-world events.
 
 Common, familiar examples include:
 
@@ -9,33 +9,20 @@ Common, familiar examples include:
 - Shuffling a deck of cards: a random ordering of a card list.
 - The creation of trees and bushes in a 3-D graphics simulation.
 
-Generating truly random values with a computer is a [surprisingly difficult technical challenge][why-randomness-is-hard], so you may see these results referred to as "pseudorandom".
+Generating truly random values with a computer is a [surprisingly difficult technical challenge][why-randomness-is-hard], which is why there are also "pseudorandom" generators.
+<!-- prettier-ignore -->
+~~~exercism/caution
+The `Math.random()` function should NOT be used for security and cryptographic applications!
+Finish the learning exercise(s) about this concept to learn more
+~~~
 
 ## Generating random numbers
 
 In Javascript, you can generate psuedorandom numbers using the [`Math.random()`][Math.random] function.
 It will return a psuedorandom floating-point number between 0 (inclusive), and 1 (exclusive).
 
-To get a random number between _min_ (inclusive) and _max_ (exclusive) you can use a function something like this:
 
-```javascript
-function getRandomInRange(min, max) {
-  return min + Math.random() * (max - min);
-}
-getRandomInRange(4, 10);
-// => 5.72
-```
 
-## Generating random integers
-
-To generate a random integer, you can use `Math.floor()` or `Math.ceil()` to turn a randomly generated number into an integer.
-
-```exercism/caution
-
-The `Math.random()` function should NOT be used for security and cryptographic applications!!
-
-Instead, you can use the Web Crypto API, which provides various cryptographic functions.
-```
 
 [why-randomness-is-hard]: https://www.malwarebytes.com/blog/news/2013/09/in-computers-are-random-numbers-really-random
 [Math.random]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random

exercises/concept/captains-log/.meta/config.json

@@ -2,6 +2,9 @@
   "authors": [
     "SneakyMallard"
   ],
+  "contributors": [
+    "SleeplessByte"
+  ],
   "files": {
     "solution": [
       "captains-log.js"

exercises/concept/captains-log/.meta/exemplar.js

@@ -1,4 +1,3 @@
-/// <reference path="./global.d.ts" />
 // @ts-check
 
 /**
@@ -7,7 +6,7 @@
  * @returns {string} the generated registry number.
  */
 export function randomShipRegistryNumber() {
-  return 'NCC-' + Math.floor(1000 + Math.random() * 9000);
+  return `NCC-${Math.floor(1000 + Math.random() * 9000)}`;
 }
 
 /**
@@ -19,12 +18,13 @@ export function randomStardate() {
   return 41000 + Math.random() * 1000;
 }
 
+const PLANET_CLASSES = 'DHJKLMNRTY';
+  
 /**
  * Generates a random planet class.
  *
  * @returns {string} a one-letter planet class.
  */
 export function randomPlanetClass() {
-  const planetClasses = ['D', 'H', 'J', 'K', 'L', 'M', 'N', 'R', 'T', 'Y'];
-  return planetClasses[Math.floor(Math.random() * 10)];
+   return PLANET_CLASSES[Math.floor(Math.random() * PLANET_CLASSES.length)];
 }

exercises/concept/captains-log/captains-log.js

@@ -1,4 +1,3 @@
-/// <reference path="./global.d.ts" />
 // @ts-check
 
 /**