From ec240463b51f0059b7b4e2c83cdefc8b4784d267 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Thu, 14 Dec 2017 23:29:12 +0200
Subject: [PATCH] Tag, lint, build

---
 README.md    | 44 ++++++++++++++++++++++++++++++++++++++++++++
 tag_database |  3 +++
 2 files changed, 47 insertions(+)

diff --git a/README.md b/README.md
index 90e814bc8..367898d9e 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,7 @@
 * [Initialize array with values](#initialize-array-with-values)
 * [Last of list](#last-of-list)
 * [Median of array of numbers](#median-of-array-of-numbers)
+* [Nth element of array](#nth-element-of-array)
 * [Pick](#pick)
 * [Shuffle array](#shuffle-array)
 * [Similarity between arrays](#similarity-between-arrays)
@@ -71,6 +72,7 @@
 * [Hamming distance](#hamming-distance)
 * [Percentile](#percentile)
 * [Powerset](#powerset)
+* [Round number to n digits](#round-number-to-n-digits)
 * [Standard deviation](#standard-deviation)
 
 ### Media
@@ -79,6 +81,7 @@
 ### Object
 * [Object from key value pairs](#object-from-key-value-pairs)
 * [Object to key value pairs](#object-to-key-value-pairs)
+* [Shallow clone object](#shallow-clone-object)
 
 ### String
 * [Anagrams of string (with duplicates)](#anagrams-of-string-with-duplicates)
@@ -394,6 +397,20 @@ const median = arr => {
 
 [⬆ back to top](#table-of-contents)
 
+### Nth element of array
+
+Use `Array.slice()` to get an array containing the nth element at the first place. 
+If the index is out of bounds, return `[]`.
+Omit the second argument, `n`, to get the first element of the array.
+
+```js
+const nth = (arr, n=0) => (n>0? arr.slice(n,n+1) : arr.slice(n))[0];
+// nth(['a','b','c'],1) -> 'b'
+// nth(['a','b','b']-2) -> 'a'
+```
+
+[⬆ back to top](#table-of-contents)
+
 ### Pick
 
 Use `Array.reduce()` to convert the filtered/picked keys back to a object with the corresponding key:value pair if the key exist in the obj.
@@ -798,6 +815,18 @@ const powerset = arr =>
 
 [⬆ back to top](#table-of-contents)
 
+### Round number to n digits
+
+Use `Math.round()` and template literals to round the number to the specified number of digits.
+Omit the second argument, `decimals` to round to an integer.
+
+```js
+const round = (n, decimals=0) => Number(`${Math.round(`${n}e${decimals}`)}e-${decimals}`);
+// round(1.005, 2) -> 1.01
+```
+
+[⬆ back to top](#table-of-contents)
+
 ### 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
@@ -858,6 +887,21 @@ const objectToPairs = obj => Object.keys(obj).map(k => [k, obj[k]]);
 // objectToPairs({a: 1, b: 2}) -> [['a',1],['b',2]])
 ```
 
+[⬆ back to top](#table-of-contents)
+
+### Shallow clone object
+
+Use the object `...spread` operator to spread the properties of the target object into the clone.
+
+```js
+const shallowClone = obj => ({ ...obj });
+/*
+const a = { x: true, y: 1 };
+const b = shallowClone(a);
+a === b -> false
+*/
+```
+
 [⬆ back to top](#table-of-contents)
 ## String
 
diff --git a/tag_database b/tag_database
index 7f81cbec1..b2535a484 100644
--- a/tag_database
+++ b/tag_database
@@ -49,6 +49,7 @@ is-symbol:utility
 last-of-list:array
 measure-time-taken-by-function:utility
 median-of-array-of-numbers:array
+nth-element-of-array:array
 number-to-array-of-digits:utility
 object-from-key-value-pairs:object
 object-to-key-value-pairs:object
@@ -63,8 +64,10 @@ random-number-in-range:utility
 redirect-to-URL:browser
 reverse-a-string:string
 RGB-to-hexadecimal:utility
+round-number-to-n-digits:math
 run-promises-in-series:function
 scroll-to-top:browser
+shallow-clone-object:object
 shuffle-array:array
 similarity-between-arrays:array
 sleep:function