From 911610949818bbd9b27d492bc551baff3506e89d Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:00:21 +1100
Subject: [PATCH 01/41] Create standard-deviation.md

http://www.calculator.net/standard-deviation-calculator.html

As a one-liner it's really long, feel free to optimize the formatting here (or shorten it further somehow).
---
 snippets/standard-deviation.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 snippets/standard-deviation.md

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
new file mode 100644
index 000000000..3ee95a147
--- /dev/null
+++ b/snippets/standard-deviation.md
@@ -0,0 +1,16 @@
+### Standard deviation
+
+Use `Array.reduce()` to calculate the mean of the values, the variance of the values, and the sum of the variance
+of the values to determine the standard deviation of an array of numbers.
+
+NOTE: This is **population standard deviation**. Use `/ (arr.length - 1)` at the end to 
+calculate **sample standard deviation**.
+
+```js
+const standardDeviation = (arr, val) =>
+  Math.sqrt(
+    arr.reduce((acc, val) => acc.concat(Math.pow(val - arr.reduce((acc, val) => acc + val, 0) / arr.length, 2)), [])
+       .reduce((acc, val) => acc + val, 0) 
+    / arr.length
+  );
+```

From 635adbc61799bfb7659448f38099adb496a80b6a Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:02:21 +1100
Subject: [PATCH 02/41] Update standard-deviation.md

---
 snippets/standard-deviation.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index 3ee95a147..63485f91e 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -13,4 +13,5 @@ const standardDeviation = (arr, val) =>
        .reduce((acc, val) => acc + val, 0) 
     / arr.length
   );
+// standardDeviation([10,2,38,23,38,23,21]) -> 12.298996142875
 ```

From 731df313959b3b47e4c9ed4da46c9fa941947608 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:12:42 +1100
Subject: [PATCH 03/41] Update standard-deviation.md

---
 snippets/standard-deviation.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index 63485f91e..0ae7f56af 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -7,7 +7,7 @@ NOTE: This is **population standard deviation**. Use `/ (arr.length - 1)` at the
 calculate **sample standard deviation**.
 
 ```js
-const standardDeviation = (arr, val) =>
+const standardDeviation = arr =>
   Math.sqrt(
     arr.reduce((acc, val) => acc.concat(Math.pow(val - arr.reduce((acc, val) => acc + val, 0) / arr.length, 2)), [])
        .reduce((acc, val) => acc + val, 0) 

From b844b0f765dbdb69783d544a39f067bb708f8744 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:41:28 +1100
Subject: [PATCH 04/41] Add usePopulation flag param

---
 snippets/standard-deviation.md | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index 0ae7f56af..a2b9a64fe 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -3,15 +3,15 @@
 Use `Array.reduce()` to calculate the mean of the values, the variance of the values, and the sum of the variance
 of the values to determine the standard deviation of an array of numbers.
 
-NOTE: This is **population standard deviation**. Use `/ (arr.length - 1)` at the end to 
-calculate **sample standard deviation**.
+Since there are two types of standard deviation, population and sample, you can use a flag to switch to population (sample is default).
 
 ```js
-const standardDeviation = arr =>
+const standardDeviation = (arr, usePopulation) =>
   Math.sqrt(
     arr.reduce((acc, val) => acc.concat(Math.pow(val - arr.reduce((acc, val) => acc + val, 0) / arr.length, 2)), [])
        .reduce((acc, val) => acc + val, 0) 
-    / arr.length
+    / (arr.length - (usePopulation ? 0 : 1))
   );
-// standardDeviation([10,2,38,23,38,23,21]) -> 12.298996142875
+// standardDeviation([10,2,38,23,38,23,21]) -> 13.284434142114991 (sample)
+// standardDeviation([10,2,38,23,38,23,21], true) -> 12.29899614287479 (population)
 ```

From 3d7b322a9d9defaf99a3f3f27aec45857697156f Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:48:29 +1100
Subject: [PATCH 05/41] Cache the mean

---
 snippets/standard-deviation.md | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index a2b9a64fe..b1dd0b9c6 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -6,12 +6,14 @@ of the values to determine the standard deviation of an array of numbers.
 Since there are two types of standard deviation, population and sample, you can use a flag to switch to population (sample is default).
 
 ```js
-const standardDeviation = (arr, usePopulation) =>
-  Math.sqrt(
-    arr.reduce((acc, val) => acc.concat(Math.pow(val - arr.reduce((acc, val) => acc + val, 0) / arr.length, 2)), [])
+const standardDeviation = (arr, usePopulation) => {
+  const mean = arr.reduce((acc, val) => acc + val, 0);
+  return Math.sqrt(
+    arr.reduce((acc, val) => acc.concat(Math.pow(val - mean / arr.length, 2)), [])
        .reduce((acc, val) => acc + val, 0) 
     / (arr.length - (usePopulation ? 0 : 1))
   );
+ }
 // standardDeviation([10,2,38,23,38,23,21]) -> 13.284434142114991 (sample)
 // standardDeviation([10,2,38,23,38,23,21], true) -> 12.29899614287479 (population)
 ```

From 418069551b528e3855d2a39a6375f70a88b36a2e Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:54:33 +1100
Subject: [PATCH 06/41] Update standard-deviation.md

---
 snippets/standard-deviation.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index b1dd0b9c6..3641cbe14 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -7,7 +7,7 @@ Since there are two types of standard deviation, population and sample, you can
 
 ```js
 const standardDeviation = (arr, usePopulation) => {
-  const mean = arr.reduce((acc, val) => acc + val, 0);
+  const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
   return Math.sqrt(
     arr.reduce((acc, val) => acc.concat(Math.pow(val - mean / arr.length, 2)), [])
        .reduce((acc, val) => acc + val, 0) 

From 98f56cbf2394b59053f14b4e4ef382c456965128 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 13 Dec 2017 23:55:08 +1100
Subject: [PATCH 07/41] Update standard-deviation.md

---
 snippets/standard-deviation.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index 3641cbe14..442052761 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -9,7 +9,7 @@ Since there are two types of standard deviation, population and sample, you can
 const standardDeviation = (arr, usePopulation) => {
   const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
   return Math.sqrt(
-    arr.reduce((acc, val) => acc.concat(Math.pow(val - mean / arr.length, 2)), [])
+    arr.reduce((acc, val) => acc.concat(Math.pow(val - mean, 2)), [])
        .reduce((acc, val) => acc + val, 0) 
     / (arr.length - (usePopulation ? 0 : 1))
   );

From 4a661d70f2eec0a2dec891d8fed38bdc5cfeaf55 Mon Sep 17 00:00:00 2001
From: iamsoorena <s.soorena@gmail.com>
Date: Thu, 14 Dec 2017 00:10:56 +0330
Subject: [PATCH 08/41] add sleep function - making delays in async functions

---
 snippets/sleep.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 snippets/sleep.md

diff --git a/snippets/sleep.md b/snippets/sleep.md
new file mode 100644
index 000000000..4a7e8916b
--- /dev/null
+++ b/snippets/sleep.md
@@ -0,0 +1,12 @@
+### Sleep
+
+If you have an async function and you want to delay executing part of it. you can put your async function to sleep(in miliseconds).
+
+```js
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+// async function sleepyWork() {
+//   console.log('I\'m going to sleep for 1 second.');
+//   await sleep(1000);
+//   console.log('I woke up after 1 second.');
+// }
+```

From e8d9acae9a3d9dd07a4e06716ceb63a2dc137a37 Mon Sep 17 00:00:00 2001
From: Elder Henrique Souza <elderhenrique@gmail.com>
Date: Wed, 13 Dec 2017 18:49:12 -0200
Subject: [PATCH 09/41] group by

Tried to reproduce the groupBy behaviour from the lodash lib.
https://lodash.com/docs/4.17.4#groupBy
---
 snippets/group-by | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 snippets/group-by

diff --git a/snippets/group-by b/snippets/group-by
new file mode 100644
index 000000000..53383db3a
--- /dev/null
+++ b/snippets/group-by
@@ -0,0 +1,16 @@
+### Group by
+
+Passing an array of values, a function or a property name thats going to be run against each value in the array,
+returns an object where the keys are the mapped results and the values is an array of the original values that generated the same results.
+
+```js
+const groupBy = (values, fn) => {
+  return (typeof fn === 'function' ? values.map(fn) : values.map((val) => val[fn]))
+    .reduce((acc, val, i) => {
+      acc[val] = acc[val] === undefined ? [values[i]] : acc[val].concat(values[i]);
+      return acc;
+    }, {});
+}
+// groupBy([6.1, 4.2, 6.3], Math.floor) -> {4: [4.2], 6: [6.1, 6.3]}
+// groupBy(['one', 'two', 'three'], 'length') -> {3: ['one', 'two'], 5: ['three']}
+```

From 8c6059098d19e25d8b415180848af40e4c648bdb Mon Sep 17 00:00:00 2001
From: Darren Scerri <darren@scerri.me>
Date: Wed, 13 Dec 2017 22:56:36 +0100
Subject: [PATCH 10/41] Remove duplicate snippets. Simplify implementation

---
 README.md                            | 24 +++++-------------------
 snippets/randomize-order-of-array.md |  8 --------
 snippets/shuffle-array-values.md     | 12 ------------
 snippets/shuffle-array.md            |  8 ++++++++
 4 files changed, 13 insertions(+), 39 deletions(-)
 delete mode 100644 snippets/randomize-order-of-array.md
 delete mode 100644 snippets/shuffle-array-values.md
 create mode 100644 snippets/shuffle-array.md

diff --git a/README.md b/README.md
index b77013e78..7317a259d 100644
--- a/README.md
+++ b/README.md
@@ -50,13 +50,12 @@
 * [Promisify](#promisify)
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
-* [Randomize order of array](#randomize-order-of-array)
 * [Redirect to url](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
 * [Scroll to top](#scroll-to-top)
-* [Shuffle array values](#shuffle-array-values)
+* [Shuffle array](#shuffle-array)
 * [Similarity between arrays](#similarity-between-arrays)
 * [Sort characters in string (alphabetical)](#sort-characters-in-string-alphabetical)
 * [Sum of array of numbers](#sum-of-array-of-numbers)
@@ -510,15 +509,6 @@ const randomInRange = (min, max) => Math.random() * (max - min) + min;
 // randomInRange(2,10) -> 6.0211363285087005
 ```
 
-### Randomize order of array
-
-Use `Array.sort()` to reorder elements, utilizing `Math.random()` to randomize the sorting.
-
-```js
-const randomizeOrder = arr => arr.sort( (a,b) => Math.random() >= 0.5 ? -1 : 1);
-// randomizeOrder([1,2,3]) -> [1,3,2]
-```
-
 ### Redirect to URL
 
 Use `window.location.href` or `window.location.replace()` to redirect to `url`.
@@ -575,17 +565,13 @@ const scrollToTop = _ => {
 // scrollToTop()
 ```
 
-### Shuffle array values
+### Shuffle array
 
-Create an array of random values by using `Array.map()` and `Math.random()`.
-Use `Array.sort()` to sort the elements of the original array based on the random values.
+Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator.
 
 ```js
-const shuffle = arr => {
-  let r = arr.map(Math.random);
-  return arr.sort((a,b) => r[a] - r[b]);
-}
-// shuffle([1,2,3]) -> [2, 1, 3]
+const shuffle = arr => arr.sort(() => Math.random() - 0.5);
+// shuffle([1,2,3]) -> [2,3,1]
 ```
 
 ### Similarity between arrays
diff --git a/snippets/randomize-order-of-array.md b/snippets/randomize-order-of-array.md
deleted file mode 100644
index d65aaf444..000000000
--- a/snippets/randomize-order-of-array.md
+++ /dev/null
@@ -1,8 +0,0 @@
-### Randomize order of array
-
-Use `Array.sort()` to reorder elements, utilizing `Math.random()` to randomize the sorting.
-
-```js
-const randomizeOrder = arr => arr.sort( (a,b) => Math.random() >= 0.5 ? -1 : 1);
-// randomizeOrder([1,2,3]) -> [1,3,2]
-```
diff --git a/snippets/shuffle-array-values.md b/snippets/shuffle-array-values.md
deleted file mode 100644
index a140bd647..000000000
--- a/snippets/shuffle-array-values.md
+++ /dev/null
@@ -1,12 +0,0 @@
-### Shuffle array values
-
-Create an array of random values by using `Array.map()` and `Math.random()`.
-Use `Array.sort()` to sort the elements of the original array based on the random values.
-
-```js
-const shuffle = arr => {
-  let r = arr.map(Math.random);
-  return arr.sort((a,b) => r[a] - r[b]);
-}
-// shuffle([1,2,3]) -> [2, 1, 3]
-```
diff --git a/snippets/shuffle-array.md b/snippets/shuffle-array.md
new file mode 100644
index 000000000..6266f9ecf
--- /dev/null
+++ b/snippets/shuffle-array.md
@@ -0,0 +1,8 @@
+### Shuffle array
+
+Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator.
+
+```js
+const shuffle = arr => arr.sort(() => Math.random() - 0.5);
+// shuffle([1,2,3]) -> [2,3,1]
+```

From 2b34ee4ba92f13c0b0d4f653e8e2fde7f1ca2601 Mon Sep 17 00:00:00 2001
From: Darren Scerri <darren@scerri.me>
Date: Thu, 14 Dec 2017 01:11:38 +0100
Subject: [PATCH 11/41] Fix names and links

---
 README.md                      | 6 +++---
 snippets/array-difference.md   | 2 +-
 snippets/array-intersection.md | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index ddd428064..7ccd59b50 100644
--- a/README.md
+++ b/README.md
@@ -55,7 +55,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to URL](#redirect-to-url)
+* [Redirect to url](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
@@ -89,7 +89,7 @@ const anagrams = str => {
 // anagrams('abc') -> ['abc','acb','bac','bca','cab','cba']
 ```
 
-### Array difference (complement)
+### Array difference
 
 Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values not contained in `b`.
 
@@ -98,7 +98,7 @@ const difference = (a, b) => { const s = new Set(b); return a.filter(x => !s.has
 // difference([1,2,3], [1,2]) -> [3]
 ```
 
-### Array intersection (Common values between two arrays)
+### Array intersection
 
 Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values contained in `b`.
 
diff --git a/snippets/array-difference.md b/snippets/array-difference.md
index 74e518f5c..46469b1d6 100644
--- a/snippets/array-difference.md
+++ b/snippets/array-difference.md
@@ -1,4 +1,4 @@
-### Array difference (complement)
+### Array difference
 
 Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values not contained in `b`.
 
diff --git a/snippets/array-intersection.md b/snippets/array-intersection.md
index 909c4312d..87c42378b 100644
--- a/snippets/array-intersection.md
+++ b/snippets/array-intersection.md
@@ -1,4 +1,4 @@
-### Array intersection (Common values between two arrays)
+### Array intersection
 
 Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values contained in `b`.
 

From 5fbfa9422c7fc29ac20e0a6b58bfc4f2e63d440f Mon Sep 17 00:00:00 2001
From: Robert Mennell <skatcat31@users.noreply.github.com>
Date: Wed, 13 Dec 2017 21:20:36 -0800
Subject: [PATCH 12/41] Update README.md

Remove the Question mark as per https://github.com/Chalarangelo/30-seconds-of-code/issues/95
---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index ddd428064..3dc91bb5e 100644
--- a/README.md
+++ b/README.md
@@ -705,7 +705,7 @@ Pass `location.search` as the argument to apply to the current `url`.
 
 ```js
 const getUrlParameters = url =>
-  url.match(/([^?=&]+)(=([^&]*))?/g).reduce(
+  url.match(/([^?=&]+)(=([^&]*))/g).reduce(
     (a, v) => (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1), a), {}
   );
 // getUrlParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}

From e421b1d49d92c1a95a30fe6fa7b157ea4a3426dd Mon Sep 17 00:00:00 2001
From: panshao <1016432619@qq.com>
Date: Thu, 14 Dec 2017 14:09:46 +0800
Subject: [PATCH 13/41] Update README.md

use Array.from instead of Array.apply
---
 README.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index ddd428064..46f4ff8e9 100644
--- a/README.md
+++ b/README.md
@@ -185,14 +185,14 @@ const palindrome = str => {
 
 ### Chunk array
 
-Use `Array.apply()` to create a new array, that fits the number of chunks that will be produced.
-Use `Array.map()` to map each element of the new array to a chunk the length of `size`.
+Use `Array.from(arrayLike[, mapFn[, thisArg]])` to create a new array, that fits the number of chunks that will be produced.
+Use `mapFn` to map each element of the new array to a chunk the length of `size`.
 If the original array can't be split evenly, the final chunk will contain the remaining elements.
 
 ```js
 const chunk = (arr, size) =>
-  Array.apply(null, {length: Math.ceil(arr.length / size)}).map((v, i) => arr.slice(i * size, i * size + size));
-// chunk([1,2,3,4,5], 2) -> [[1,2],[3,4],5]
+  Array.from({length: Math.ceil(arr.length / size)}, (v, i) => arr.slice(i * size, i * size + size));
+  // chunk([1,2,3,4,5], 2) -> [[1,2],[3,4],5]
 ```
 
 ### Count occurrences of a value in array

From 81f7e8e9ed5564859b9a33813a7b371ec3cede1e Mon Sep 17 00:00:00 2001
From: Huseyin Sekmenoglu <sekmenhuseyin@users.noreply.github.com>
Date: Thu, 14 Dec 2017 10:57:17 +0300
Subject: [PATCH 14/41] Create validate-email.md

---
 snippets/validate-email.md | 10 ++++++++++
 1 file changed, 10 insertions(+)
 create mode 100644 snippets/validate-email.md

diff --git a/snippets/validate-email.md b/snippets/validate-email.md
new file mode 100644
index 000000000..57a8afd2a
--- /dev/null
+++ b/snippets/validate-email.md
@@ -0,0 +1,10 @@
+### Validate Email
+ 
+ Regex is taken from https://stackoverflow.com/questions/46155/how-to-validate-email-address-in-javascript
+ Returns `true` if email is valid, `false` if not.
+ 
+ ```js
+ const validateEmail = str => /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(str);
+ // isemail(mymail@gmail.com) -> true
+ ```
+ 

From 494189089e7c760da4bde2e65c6d5ed8f81793c3 Mon Sep 17 00:00:00 2001
From: Robert Mennell <skatcat31@users.noreply.github.com>
Date: Wed, 13 Dec 2017 21:20:36 -0800
Subject: [PATCH 15/41] Revert "Update README.md"

This reverts commit 682f172645a7b16f640f966f25b02de0cd12f55b.
---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 3dc91bb5e..ddd428064 100644
--- a/README.md
+++ b/README.md
@@ -705,7 +705,7 @@ Pass `location.search` as the argument to apply to the current `url`.
 
 ```js
 const getUrlParameters = url =>
-  url.match(/([^?=&]+)(=([^&]*))/g).reduce(
+  url.match(/([^?=&]+)(=([^&]*))?/g).reduce(
     (a, v) => (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1), a), {}
   );
 // getUrlParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}

From e6bfe6606f9ef20468d667cadd7a478bcf80cede Mon Sep 17 00:00:00 2001
From: Robert Mennell <skatcat31@gmail.com>
Date: Thu, 14 Dec 2017 00:23:14 -0800
Subject: [PATCH 16/41] Fix: remove one or more quantifier from Match to
 properly pull out parts

---
 snippets/URL-parameters.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/URL-parameters.md b/snippets/URL-parameters.md
index 742e7ffbd..f78c774d8 100644
--- a/snippets/URL-parameters.md
+++ b/snippets/URL-parameters.md
@@ -5,7 +5,7 @@ Pass `location.search` as the argument to apply to the current `url`.
 
 ```js
 const getUrlParameters = url =>
-  url.match(/([^?=&]+)(=([^&]*))?/g).reduce(
+  url.match(/([^?=&]+)(=([^&]*))/g).reduce(
     (a, v) => (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1), a), {}
   );
 // getUrlParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}

From 3fae1fa34a953bf262f02fc9ed69df7ac34d4553 Mon Sep 17 00:00:00 2001
From: King <kingdavidmartins@users.noreply.github.com>
Date: Thu, 14 Dec 2017 03:24:05 -0500
Subject: [PATCH 17/41] update description of head & ran npm run build-list

---
 README.md                | 4 ++--
 snippets/head-of-list.md | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 458bf5611..c26a5677d 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to URL](#redirect-to-url)
+* [Redirect to url](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
@@ -395,7 +395,7 @@ const hammingDistance = (num1, num2) =>
 
 ### Head of list
 
-Return `arr[0]`.
+Use `arr[0]` to return the first element of the passed array.
 
 ```js
 const head = arr => arr[0];
diff --git a/snippets/head-of-list.md b/snippets/head-of-list.md
index 31dc5fbaf..c2e0d5a3a 100644
--- a/snippets/head-of-list.md
+++ b/snippets/head-of-list.md
@@ -1,6 +1,6 @@
 ### Head of list
 
-Return `arr[0]`.
+Use `arr[0]` to return the first element of the passed array.
 
 ```js
 const head = arr => arr[0];

From 3ce9c180c59c35a0446c1296cf9072ebf93e5b60 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:26:08 +0200
Subject: [PATCH 18/41] Build README

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index a125ed5c6..850d944cf 100644
--- a/README.md
+++ b/README.md
@@ -732,7 +732,7 @@ Pass `location.search` as the argument to apply to the current `url`.
 
 ```js
 const getUrlParameters = url =>
-  url.match(/([^?=&]+)(=([^&]*))?/g).reduce(
+  url.match(/([^?=&]+)(=([^&]*))/g).reduce(
     (a, v) => (a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1), a), {}
   );
 // getUrlParameters('http://url.com/page?name=Adam&surname=Smith') -> {name: 'Adam', surname: 'Smith'}

From 80af3e7c6d06b9baa743b477226b675b4391880e Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:28:09 +0200
Subject: [PATCH 19/41] Build README

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index af1cd5ccb..4dbfe200a 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to url](#redirect-to-url)
+* [Redirect to URL](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)

From e98fd5fe3ab0aa76168d5898ca51d813c5f67df5 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:32:59 +0200
Subject: [PATCH 20/41] Build README

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 476f862a9..88d89840c 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to url](#redirect-to-url)
+* [Redirect to URL](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)

From 9980dbac0f596e99e08853057e88a4d49f0caa1d Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:34:29 +0200
Subject: [PATCH 21/41] Update sleep.md

---
 snippets/sleep.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/sleep.md b/snippets/sleep.md
index 4a7e8916b..c64ed3917 100644
--- a/snippets/sleep.md
+++ b/snippets/sleep.md
@@ -1,6 +1,6 @@
 ### Sleep
 
-If you have an async function and you want to delay executing part of it. you can put your async function to sleep(in miliseconds).
+Delay executing part of an `async` function, by putting it to sleep, returning a `Promise`.
 
 ```js
 const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));

From 27c02041fd0ed0afc685d5d771cd31d440689afa Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:35:58 +0200
Subject: [PATCH 22/41] Build README

---
 README.md         | 16 ++++++++++++++++
 snippets/sleep.md | 12 +++++++-----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index 88d89840c..8b9c31e13 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,7 @@
 * [Scroll to top](#scroll-to-top)
 * [Shuffle array values](#shuffle-array-values)
 * [Similarity between arrays](#similarity-between-arrays)
+* [Sleep](#sleep)
 * [Sort characters in string (alphabetical)](#sort-characters-in-string-alphabetical)
 * [Sum of array of numbers](#sum-of-array-of-numbers)
 * [Swap values of two variables](#swap-values-of-two-variables)
@@ -667,6 +668,21 @@ const similarity = (arr, values) => arr.filter(v => values.includes(v));
 // similarity([1,2,3], [1,2,4]) -> [1,2]
 ```
 
+### Sleep
+
+Delay executing part of an `async` function, by putting it to sleep, returning a `Promise`.
+
+```js
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+/*
+async function sleepyWork() {
+  console.log('I\'m going to sleep for 1 second.');
+  await sleep(1000);
+  console.log('I woke up after 1 second.');
+}
+*/
+```
+
 ### Sort characters in string (alphabetical)
 
 Split the string using `split('')`, `Array.sort()` utilizing `localeCompare()`, recombine using `join('')`.
diff --git a/snippets/sleep.md b/snippets/sleep.md
index c64ed3917..e2a58d0bd 100644
--- a/snippets/sleep.md
+++ b/snippets/sleep.md
@@ -4,9 +4,11 @@ Delay executing part of an `async` function, by putting it to sleep, returning a
 
 ```js
 const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
-// async function sleepyWork() {
-//   console.log('I\'m going to sleep for 1 second.');
-//   await sleep(1000);
-//   console.log('I woke up after 1 second.');
-// }
+/*
+async function sleepyWork() {
+  console.log('I\'m going to sleep for 1 second.');
+  await sleep(1000);
+  console.log('I woke up after 1 second.');
+}
+*/
 ```

From 755425f5562215404aef5cd59a9d00eeb16246de Mon Sep 17 00:00:00 2001
From: King <kingdavidmartins@users.noreply.github.com>
Date: Thu, 14 Dec 2017 03:44:45 -0500
Subject: [PATCH 23/41] ran npm run build-list & update intial-of-list
 description

---
 README.md                   | 4 ++--
 snippets/initial-of-list.md | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 8b9c31e13..f370a585a 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to URL](#redirect-to-url)
+* [Redirect to url](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
@@ -405,7 +405,7 @@ const head = arr => arr[0];
 
 ### Initial of list
 
-Return `arr.slice(0,-1)`.
+Use `arr.slice(0,-1)`to return all but the last element of the array.
 
 ```js
 const initial = arr => arr.slice(0, -1);
diff --git a/snippets/initial-of-list.md b/snippets/initial-of-list.md
index a222f2306..1f967f804 100644
--- a/snippets/initial-of-list.md
+++ b/snippets/initial-of-list.md
@@ -1,6 +1,6 @@
 ### Initial of list
 
-Return `arr.slice(0,-1)`.
+Use `arr.slice(0,-1)`to return all but the last element of the array.
 
 ```js
 const initial = arr => arr.slice(0, -1);

From 91f393207df999ed0ef1cf715f08426d570bd426 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:45:09 +0200
Subject: [PATCH 24/41] Update group-by

Shortened code. It now also follows the styleguide more precisely. Improved description.
---
 snippets/group-by | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/snippets/group-by b/snippets/group-by
index 53383db3a..e6df1a2a7 100644
--- a/snippets/group-by
+++ b/snippets/group-by
@@ -1,16 +1,14 @@
 ### Group by
 
-Passing an array of values, a function or a property name thats going to be run against each value in the array,
-returns an object where the keys are the mapped results and the values is an array of the original values that generated the same results.
+Use `Array.map()` to map the values of an array to a function or property name.
+Use `Array.reduce()` to create an object, where the keys are produced from the mapped results.
 
 ```js
-const groupBy = (values, fn) => {
-  return (typeof fn === 'function' ? values.map(fn) : values.map((val) => val[fn]))
+const groupBy = (arr, func) => 
+  (typeof func === 'function' ? arr.map(func) : arr.map(val => val[func]))
     .reduce((acc, val, i) => {
-      acc[val] = acc[val] === undefined ? [values[i]] : acc[val].concat(values[i]);
-      return acc;
+      acc[val] = acc[val] === undefined ? [arr[i]] : acc[val].concat(arr[i]); return acc;
     }, {});
-}
 // groupBy([6.1, 4.2, 6.3], Math.floor) -> {4: [4.2], 6: [6.1, 6.3]}
 // groupBy(['one', 'two', 'three'], 'length') -> {3: ['one', 'two'], 5: ['three']}
 ```

From 2afdce90ee3d55ce14ce9a8d8e0bb7614e1accc3 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:46:46 +0200
Subject: [PATCH 25/41] Build README

---
 README.md                          | 16 ++++++++++++++++
 snippets/{group-by => group-by.md} |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)
 rename snippets/{group-by => group-by.md} (94%)

diff --git a/README.md b/README.md
index 8b9c31e13..522f36584 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,7 @@
 * [Get native type of value](#get-native-type-of-value)
 * [Get scroll position](#get-scroll-position)
 * [Greatest common divisor (GCD)](#greatest-common-divisor-gcd)
+* [Group by](#group-by)
 * [Hamming distance](#hamming-distance)
 * [Head of list](#head-of-list)
 * [Initial of list](#initial-of-list)
@@ -383,6 +384,21 @@ const gcd = (x, y) => !y ? x : gcd(y, x % y);
 // gcd (8, 36) -> 4
 ```
 
+### Group by
+
+Use `Array.map()` to map the values of an array to a function or property name.
+Use `Array.reduce()` to create an object, where the keys are produced from the mapped results.
+
+```js
+const groupBy = (arr, func) =>
+  (typeof func === 'function' ? arr.map(func) : arr.map(val => val[func]))
+    .reduce((acc, val, i) => {
+      acc[val] = acc[val] === undefined ? [arr[i]] : acc[val].concat(arr[i]); return acc;
+    }, {});
+// groupBy([6.1, 4.2, 6.3], Math.floor) -> {4: [4.2], 6: [6.1, 6.3]}
+// groupBy(['one', 'two', 'three'], 'length') -> {3: ['one', 'two'], 5: ['three']}
+```
+
 ### Hamming distance
 
 Use XOR operator (`^`) to find the bit difference between the two numbers, convert to binary string using `toString(2)`.
diff --git a/snippets/group-by b/snippets/group-by.md
similarity index 94%
rename from snippets/group-by
rename to snippets/group-by.md
index e6df1a2a7..ab833c9d2 100644
--- a/snippets/group-by
+++ b/snippets/group-by.md
@@ -4,7 +4,7 @@ Use `Array.map()` to map the values of an array to a function or property name.
 Use `Array.reduce()` to create an object, where the keys are produced from the mapped results.
 
 ```js
-const groupBy = (arr, func) => 
+const groupBy = (arr, func) =>
   (typeof func === 'function' ? arr.map(func) : arr.map(val => val[func]))
     .reduce((acc, val, i) => {
       acc[val] = acc[val] === undefined ? [arr[i]] : acc[val].concat(arr[i]); return acc;

From 2123d8d50a72b26003f1d8525426c84265cab871 Mon Sep 17 00:00:00 2001
From: King <kingdavidmartins@users.noreply.github.com>
Date: Thu, 14 Dec 2017 03:49:18 -0500
Subject: [PATCH 26/41] update last-of-list & ran npm run build-list

---
 README.md                | 4 ++--
 snippets/last-of-list.md | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 8b9c31e13..d267e205a 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to URL](#redirect-to-url)
+* [Redirect to url](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
@@ -435,7 +435,7 @@ const initializeArray = (n, value = 0) => Array(n).fill(value);
 
 ### Last of list
 
-Return `arr.slice(-1)[0]`.
+Use `arr.slice(-1)[0]` to get the last element of the given array.
 
 ```js
 const last = arr => arr.slice(-1)[0];
diff --git a/snippets/last-of-list.md b/snippets/last-of-list.md
index 16955f201..d27b0b35e 100644
--- a/snippets/last-of-list.md
+++ b/snippets/last-of-list.md
@@ -1,6 +1,6 @@
 ### Last of list
 
-Return `arr.slice(-1)[0]`.
+Use `arr.slice(-1)[0]` to get the last element of the given array.
 
 ```js
 const last = arr => arr.slice(-1)[0];

From 3b0fa08fdd5052e15759c92263218449d0d1b5f7 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 10:59:20 +0200
Subject: [PATCH 27/41] Build README

---
 README.md               | 8 ++++----
 snippets/chunk-array.md | 6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index e3d9727df..dd66eebff 100644
--- a/README.md
+++ b/README.md
@@ -58,7 +58,7 @@
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
 * [Randomize order of array](#randomize-order-of-array)
-* [Redirect to url](#redirect-to-url)
+* [Redirect to URL](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
@@ -189,14 +189,14 @@ const palindrome = str => {
 
 ### Chunk array
 
-Use `Array.from(arrayLike[, mapFn[, thisArg]])` to create a new array, that fits the number of chunks that will be produced.
-Use `mapFn` to map each element of the new array to a chunk the length of `size`.
+Use `Array.from()` to create a new array, that fits the number of chunks that will be produced.
+Use `Array.slice()` to map each element of the new array to a chunk the length of `size`.
 If the original array can't be split evenly, the final chunk will contain the remaining elements.
 
 ```js
 const chunk = (arr, size) =>
   Array.from({length: Math.ceil(arr.length / size)}, (v, i) => arr.slice(i * size, i * size + size));
-  // chunk([1,2,3,4,5], 2) -> [[1,2],[3,4],5]
+// chunk([1,2,3,4,5], 2) -> [[1,2],[3,4],5]
 ```
 
 ### Compact
diff --git a/snippets/chunk-array.md b/snippets/chunk-array.md
index de6c5a568..c14bf269d 100644
--- a/snippets/chunk-array.md
+++ b/snippets/chunk-array.md
@@ -1,11 +1,11 @@
 ### Chunk array
 
-Use `Array.apply()` to create a new array, that fits the number of chunks that will be produced.
-Use `Array.map()` to map each element of the new array to a chunk the length of `size`.
+Use `Array.from()` to create a new array, that fits the number of chunks that will be produced.
+Use `Array.slice()` to map each element of the new array to a chunk the length of `size`.
 If the original array can't be split evenly, the final chunk will contain the remaining elements.
 
 ```js
 const chunk = (arr, size) =>
-  Array.apply(null, {length: Math.ceil(arr.length / size)}).map((v, i) => arr.slice(i * size, i * size + size));
+  Array.from({length: Math.ceil(arr.length / size)}, (v, i) => arr.slice(i * size, i * size + size));
 // chunk([1,2,3,4,5], 2) -> [[1,2],[3,4],5]
 ```

From f8d55631c6a5d9e4790d30347b45d675c1b0e10c Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:10:47 +0200
Subject: [PATCH 28/41] Merge pull request #88 from darrenscerri/shuffle

---
 README.md                            |  7 +++----
 snippets/randomize-order-of-array.md |  8 --------
 snippets/shuffle-array-values.md     | 12 ------------
 snippets/shuffle-array.md            |  8 ++++++++
 4 files changed, 11 insertions(+), 24 deletions(-)
 delete mode 100644 snippets/randomize-order-of-array.md
 delete mode 100644 snippets/shuffle-array-values.md
 create mode 100644 snippets/shuffle-array.md

diff --git a/README.md b/README.md
index dd66eebff..efc81a9de 100644
--- a/README.md
+++ b/README.md
@@ -63,7 +63,7 @@
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
 * [Scroll to top](#scroll-to-top)
-* [Shuffle array values](#shuffle-array-values)
+* [Shuffle array](#shuffle-array)
 * [Similarity between arrays](#similarity-between-arrays)
 * [Sleep](#sleep)
 * [Sort characters in string (alphabetical)](#sort-characters-in-string-alphabetical)
@@ -662,10 +662,9 @@ const scrollToTop = _ => {
 // scrollToTop()
 ```
 
-### Shuffle array values
+### Shuffle array
 
-Create an array of random values by using `Array.map()` and `Math.random()`.
-Use `Array.sort()` to sort the elements of the original array based on the random values.
+Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator.
 
 ```js
 const shuffle = arr => {
diff --git a/snippets/randomize-order-of-array.md b/snippets/randomize-order-of-array.md
deleted file mode 100644
index 456a00607..000000000
--- a/snippets/randomize-order-of-array.md
+++ /dev/null
@@ -1,8 +0,0 @@
-### Randomize order of array
-
-Use `Array.sort()` to reorder elements, utilizing `Math.random()` to randomize the sorting.
-
-```js
-const randomizeOrder = arr => arr.sort((a, b) => Math.random() >= 0.5 ? -1 : 1);
-// randomizeOrder([1,2,3]) -> [1,3,2]
-```
diff --git a/snippets/shuffle-array-values.md b/snippets/shuffle-array-values.md
deleted file mode 100644
index ab3698a31..000000000
--- a/snippets/shuffle-array-values.md
+++ /dev/null
@@ -1,12 +0,0 @@
-### Shuffle array values
-
-Create an array of random values by using `Array.map()` and `Math.random()`.
-Use `Array.sort()` to sort the elements of the original array based on the random values.
-
-```js
-const shuffle = arr => {
-  let r = arr.map(Math.random);
-  return arr.sort((a, b) => r[a] - r[b]);
-};
-// shuffle([1,2,3]) -> [2, 1, 3]
-```
diff --git a/snippets/shuffle-array.md b/snippets/shuffle-array.md
new file mode 100644
index 000000000..6266f9ecf
--- /dev/null
+++ b/snippets/shuffle-array.md
@@ -0,0 +1,8 @@
+### Shuffle array
+
+Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator.
+
+```js
+const shuffle = arr => arr.sort(() => Math.random() - 0.5);
+// shuffle([1,2,3]) -> [2,3,1]
+```

From a528b7f7093c748d7cedf87d0338a9d850753bad Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:15:49 +0200
Subject: [PATCH 29/41] Build README

---
 README.md | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/README.md b/README.md
index efc81a9de..db026b6c2 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,6 @@
 * [Promisify](#promisify)
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
-* [Randomize order of array](#randomize-order-of-array)
 * [Redirect to URL](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
@@ -597,15 +596,6 @@ const randomInRange = (min, max) => Math.random() * (max - min) + min;
 // randomInRange(2,10) -> 6.0211363285087005
 ```
 
-### Randomize order of array
-
-Use `Array.sort()` to reorder elements, utilizing `Math.random()` to randomize the sorting.
-
-```js
-const randomizeOrder = arr => arr.sort((a, b) => Math.random() >= 0.5 ? -1 : 1);
-// randomizeOrder([1,2,3]) -> [1,3,2]
-```
-
 ### Redirect to URL
 
 Use `window.location.href` or `window.location.replace()` to redirect to `url`.
@@ -667,11 +657,8 @@ const scrollToTop = _ => {
 Use `Array.sort()` to reorder elements, using `Math.random()` in the comparator.
 
 ```js
-const shuffle = arr => {
-  let r = arr.map(Math.random);
-  return arr.sort((a, b) => r[a] - r[b]);
-};
-// shuffle([1,2,3]) -> [2, 1, 3]
+const shuffle = arr => arr.sort(() => Math.random() - 0.5);
+// shuffle([1,2,3]) -> [2,3,1]
 ```
 
 ### Similarity between arrays

From 66702ee4764080e9a355076b430603ff26168d56 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:23:21 +0200
Subject: [PATCH 30/41] Update validate-email.md

---
 snippets/validate-email.md | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/snippets/validate-email.md b/snippets/validate-email.md
index 57a8afd2a..b4037d4aa 100644
--- a/snippets/validate-email.md
+++ b/snippets/validate-email.md
@@ -1,10 +1,11 @@
-### Validate Email
+### Validate email
  
- Regex is taken from https://stackoverflow.com/questions/46155/how-to-validate-email-address-in-javascript
- Returns `true` if email is valid, `false` if not.
+Use a regular experssion to check if the email is valid.
+Returns `true` if email is valid, `false` if not.
  
  ```js
- const validateEmail = str => /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(str);
+const validateEmail = str => 
+  /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(str);
  // isemail(mymail@gmail.com) -> true
  ```
  

From bede528c5265c304f14f0064030b310f40ac9536 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Thu, 14 Dec 2017 20:24:07 +1100
Subject: [PATCH 31/41] Use explicit default value

---
 snippets/standard-deviation.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index 442052761..f07cb4f4c 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -6,7 +6,7 @@ of the values to determine the standard deviation of an array of numbers.
 Since there are two types of standard deviation, population and sample, you can use a flag to switch to population (sample is default).
 
 ```js
-const standardDeviation = (arr, usePopulation) => {
+const standardDeviation = (arr, usePopulation = false) => {
   const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
   return Math.sqrt(
     arr.reduce((acc, val) => acc.concat(Math.pow(val - mean, 2)), [])

From 3fa2d41ff33ec1a0e9f13b81c757356e0a9cc938 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:24:46 +0200
Subject: [PATCH 32/41] Build README

---
 README.md                  | 12 ++++++++++++
 snippets/validate-email.md | 13 ++++++-------
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index db026b6c2..befac0394 100644
--- a/README.md
+++ b/README.md
@@ -73,6 +73,7 @@
 * [Unique values of array](#unique-values-of-array)
 * [URL parameters](#url-parameters)
 * [UUID generator](#uuid-generator)
+* [Validate email](#validate-email)
 * [Validate number](#validate-number)
 * [Value or default](#value-or-default)
 
@@ -768,6 +769,17 @@ const uuid = _ =>
 // uuid() -> '7982fcfe-5721-4632-bede-6000885be57d'
 ```
 
+### Validate email
+
+Use a regular experssion to check if the email is valid.
+Returns `true` if email is valid, `false` if not.
+
+```js
+const validateEmail = str =>
+  /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(str);
+// validateEmail(mymail@gmail.com) -> true
+```
+
 ### Validate number
 
 Use `!isNaN` in combination with `parseFloat()` to check if the argument is a number.
diff --git a/snippets/validate-email.md b/snippets/validate-email.md
index b4037d4aa..d83a41904 100644
--- a/snippets/validate-email.md
+++ b/snippets/validate-email.md
@@ -1,11 +1,10 @@
 ### Validate email
- 
+
 Use a regular experssion to check if the email is valid.
 Returns `true` if email is valid, `false` if not.
- 
- ```js
-const validateEmail = str => 
+
+```js
+const validateEmail = str =>
   /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(str);
- // isemail(mymail@gmail.com) -> true
- ```
- 
+// validateEmail(mymail@gmail.com) -> true
+```

From 2c30c0afdefb9fc194bd0142d2734e24ec6dc689 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:29:20 +0200
Subject: [PATCH 33/41] Update standard-deviation.md

---
 snippets/standard-deviation.md | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/snippets/standard-deviation.md b/snippets/standard-deviation.md
index f07cb4f4c..e559972bb 100644
--- a/snippets/standard-deviation.md
+++ b/snippets/standard-deviation.md
@@ -1,17 +1,15 @@
 ### Standard deviation
 
-Use `Array.reduce()` to calculate the mean of the values, the variance of the values, and the sum of the variance
-of the values to determine the standard deviation of an array of numbers.
-
-Since there are two types of standard deviation, population and sample, you can use a flag to switch to population (sample is default).
+Use `Array.reduce()` to calculate the mean, variance and the sum of the variance of the values, the variance of the values, then
+determine the standard deviation.
+You can omit the second argument to get the sample standard deviation or set it to `true` to get the population standard deviation.
 
 ```js
 const standardDeviation = (arr, usePopulation = false) => {
   const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
   return Math.sqrt(
     arr.reduce((acc, val) => acc.concat(Math.pow(val - mean, 2)), [])
-       .reduce((acc, val) => acc + val, 0) 
-    / (arr.length - (usePopulation ? 0 : 1))
+       .reduce((acc, val) => acc + val, 0) / (arr.length - (usePopulation ? 0 : 1))
   );
  }
 // standardDeviation([10,2,38,23,38,23,21]) -> 13.284434142114991 (sample)

From 0f775ba97b25ca1b3e3ec0d4c1b76b7569da2941 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:30:00 +0200
Subject: [PATCH 34/41] Build README

---
 README.md | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/README.md b/README.md
index befac0394..d0393e21a 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,7 @@
 * [Similarity between arrays](#similarity-between-arrays)
 * [Sleep](#sleep)
 * [Sort characters in string (alphabetical)](#sort-characters-in-string-alphabetical)
+* [Standard deviation](#standard-deviation)
 * [Sum of array of numbers](#sum-of-array-of-numbers)
 * [Swap values of two variables](#swap-values-of-two-variables)
 * [Tail of list](#tail-of-list)
@@ -696,6 +697,24 @@ const sortCharactersInString = str =>
 // sortCharactersInString('cabbage') -> 'aabbceg'
 ```
 
+### Standard deviation
+
+Use `Array.reduce()` to calculate the mean, variance and the sum of the variance of the values, the variance of the values, then
+determine the standard deviation.
+You can omit the second argument to get the sample standard deviation or set it to `true` to get the population standard deviation.
+
+```js
+const standardDeviation = (arr, usePopulation = false) => {
+  const mean = arr.reduce((acc, val) => acc + val, 0) / arr.length;
+  return Math.sqrt(
+    arr.reduce((acc, val) => acc.concat(Math.pow(val - mean, 2)), [])
+       .reduce((acc, val) => acc + val, 0) / (arr.length - (usePopulation ? 0 : 1))
+  );
+ }
+// standardDeviation([10,2,38,23,38,23,21]) -> 13.284434142114991 (sample)
+// standardDeviation([10,2,38,23,38,23,21], true) -> 12.29899614287479 (population)
+```
+
 ### Sum of array of numbers
 
 Use `Array.reduce()` to add each value to an accumulator, initialized with a value of `0`.

From 8ca776aa03843deca3dfc5c6fd18f89259762b2f Mon Sep 17 00:00:00 2001
From: King <kingdavidmartins@users.noreply.github.com>
Date: Thu, 14 Dec 2017 04:35:14 -0500
Subject: [PATCH 35/41] ran npm run build-list & add take.md

---
 README.md        | 14 +++++++++++++-
 snippets/take.md | 10 ++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 snippets/take.md

diff --git a/README.md b/README.md
index d0393e21a..3abae27c6 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Promisify](#promisify)
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
-* [Redirect to URL](#redirect-to-url)
+* [Redirect to url](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)
@@ -70,6 +70,7 @@
 * [Sum of array of numbers](#sum-of-array-of-numbers)
 * [Swap values of two variables](#swap-values-of-two-variables)
 * [Tail of list](#tail-of-list)
+* [Take](#take)
 * [Truncate a string](#truncate-a-string)
 * [Unique values of array](#unique-values-of-array)
 * [URL parameters](#url-parameters)
@@ -743,6 +744,17 @@ const tail = arr => arr.length > 1 ? arr.slice(1) : arr;
 // tail([1]) -> [1]
 ```
 
+### Take
+
+Use `.slice()` to create a slice of the array with n elements taken from the beginning.
+
+```js
+const take = (arr, n) => n === undefined ? arr.slice(0, 1) : arr.slice(0, n);
+
+// take([1, 2, 3], 5) -> [1, 2, 3]
+// take([1, 2, 3], 0) -> []
+```
+
 ### Truncate a String
 
 Determine if the string's `length` is greater than `num`.
diff --git a/snippets/take.md b/snippets/take.md
new file mode 100644
index 000000000..1cc7e77fe
--- /dev/null
+++ b/snippets/take.md
@@ -0,0 +1,10 @@
+### Take
+
+Use `.slice()` to create a slice of the array with n elements taken from the beginning.
+
+```js
+const take = (arr, n) => n === undefined ? arr.slice(0, 1) : arr.slice(0, n);
+
+// take([1, 2, 3], 5) -> [1, 2, 3]
+// take([1, 2, 3], 0) -> []
+```

From 236616efea4cbc88a0bde56b186addc4d19ce78b Mon Sep 17 00:00:00 2001
From: King <kingdavidmartins@users.noreply.github.com>
Date: Thu, 14 Dec 2017 04:46:16 -0500
Subject: [PATCH 36/41] refactor take

---
 README.md        | 2 +-
 snippets/take.md | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 3abae27c6..4a1ea0529 100644
--- a/README.md
+++ b/README.md
@@ -749,7 +749,7 @@ const tail = arr => arr.length > 1 ? arr.slice(1) : arr;
 Use `.slice()` to create a slice of the array with n elements taken from the beginning.
 
 ```js
-const take = (arr, n) => n === undefined ? arr.slice(0, 1) : arr.slice(0, n);
+const take = (arr, n = 1) => arr.slice(0, n);
 
 // take([1, 2, 3], 5) -> [1, 2, 3]
 // take([1, 2, 3], 0) -> []
diff --git a/snippets/take.md b/snippets/take.md
index 1cc7e77fe..f597728ea 100644
--- a/snippets/take.md
+++ b/snippets/take.md
@@ -3,7 +3,7 @@
 Use `.slice()` to create a slice of the array with n elements taken from the beginning.
 
 ```js
-const take = (arr, n) => n === undefined ? arr.slice(0, 1) : arr.slice(0, n);
+const take = (arr, n = 1) => arr.slice(0, n);
 
 // take([1, 2, 3], 5) -> [1, 2, 3]
 // take([1, 2, 3], 0) -> []

From db28e1ee28385d8946e09ebdcf6f30da1b0b7507 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:50:52 +0200
Subject: [PATCH 37/41] Update take.md

---
 snippets/take.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/take.md b/snippets/take.md
index f597728ea..80142031d 100644
--- a/snippets/take.md
+++ b/snippets/take.md
@@ -1,6 +1,6 @@
 ### Take
 
-Use `.slice()` to create a slice of the array with n elements taken from the beginning.
+Use `Array.slice()` to create a slice of the array with `n` elements taken from the beginning.
 
 ```js
 const take = (arr, n = 1) => arr.slice(0, n);

From a93268e5969c77c38d9a587056581cb39f2b0835 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:51:24 +0200
Subject: [PATCH 38/41] Update README.md

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 4a1ea0529..0c9b72501 100644
--- a/README.md
+++ b/README.md
@@ -746,7 +746,7 @@ const tail = arr => arr.length > 1 ? arr.slice(1) : arr;
 
 ### Take
 
-Use `.slice()` to create a slice of the array with n elements taken from the beginning.
+Use `Array.slice()` to create a slice of the array with `n` elements taken from the beginning.
 
 ```js
 const take = (arr, n = 1) => arr.slice(0, n);

From f7095814f4cfa4b4c278caa7dec3be7383c3ebc3 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 11:55:45 +0200
Subject: [PATCH 39/41] Build README

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 0c9b72501..1015e7c72 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@
 * [Promisify](#promisify)
 * [Random integer in range](#random-integer-in-range)
 * [Random number in range](#random-number-in-range)
-* [Redirect to url](#redirect-to-url)
+* [Redirect to URL](#redirect-to-url)
 * [Reverse a string](#reverse-a-string)
 * [RGB to hexadecimal](#rgb-to-hexadecimal)
 * [Run promises in series](#run-promises-in-series)

From 9ebbe62fb97a06d53df8014e196a2ef0e4d7f124 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 12:16:25 +0200
Subject: [PATCH 40/41] Update concat.md

Improved description a little.
---
 snippets/concat.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/concat.md b/snippets/concat.md
index 0f6c8bcb1..677bc8871 100644
--- a/snippets/concat.md
+++ b/snippets/concat.md
@@ -1,6 +1,6 @@
 ### Concat
 
-Creates a new array concatenating array with any additional arrays and/or values `args` using `Array.concat()`.
+Use `Array.concat()` to concatenate and array with any additional arrays and/or values, specified in `args`.
 
 ```js
 const ArrayConcat = (arr, ...args) => arr.concat(...args); 

From 67761753118ebf460a4a0fb1dcaa336c7abce129 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 12:17:11 +0200
Subject: [PATCH 41/41] Update and rename concat.md to array-concatenation.md

---
 snippets/{concat.md => array-concatenation.md} | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 rename snippets/{concat.md => array-concatenation.md} (90%)

diff --git a/snippets/concat.md b/snippets/array-concatenation.md
similarity index 90%
rename from snippets/concat.md
rename to snippets/array-concatenation.md
index 677bc8871..39d978d6e 100644
--- a/snippets/concat.md
+++ b/snippets/array-concatenation.md
@@ -1,4 +1,4 @@
-### Concat
+### Array concatenation
 
 Use `Array.concat()` to concatenate and array with any additional arrays and/or values, specified in `args`.