Travis build: 1010

README.md

@@ -340,6 +340,15 @@ average(1, 2, 3);
 
 </details>
 
+### _Uncategorized_
+
+<details>
+<summary>View contents</summary>
+
+* [`luhnCheck`](#luhncheck)
+
+</details>
+
 ---
  ## 🔌 Adapter
 
@@ -5358,6 +5367,40 @@ yesNo('Foo', true); // true
 
 <br>[⬆ Back to top](#table-of-contents)
 
+---
+ ## _Uncategorized_
+
+### luhnCheck
+
+Implementation of the [Luhn Algorithm](https://en.wikipedia.org/wiki/Luhn_algorithm) used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers etc.
+
+Use `String.split('')`, `Array.reverse()` and `Array.map()` in combination with `parseInt()` to obtain an array of digits.
+Use `Array.splice(0,1)` to obtain the last digit.
+Use `Array.reduce()` to implement the Luhn Algorithm.
+Return `true` if `sum` is divisible by `10`, `false` otherwise.
+
+
+```js
+const luhnCheck = num => {
+  let arr = (num + '')
+    .split('')
+    .reverse()
+    .map(x => parseInt(x));
+  let lastDigit = arr.splice(0, 1)[0];
+  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + (val * 2) % 9 || 9), 0);
+  sum += lastDigit;
+  return sum % 10 === 0;
+};
+```
+
+```js
+luhnCheck('4485275742308327'); // true
+luhnCheck(6011329933655299); //  true
+luhnCheck(123456789); // false
+```
+
+<br>[⬆ back to top](#table-of-contents)
+
 
 ## Collaborators
 

snippets/luhnCheck.md

@@ -10,16 +10,19 @@ Return `true` if `sum` is divisible by `10`, `false` otherwise.
 
 ```js
 const luhnCheck = num => {
-  let arr = (num+'').split('').reverse().map(x => parseInt(x));
+  let arr = (num + '')
+    .split('')
+    .reverse()
+    .map(x => parseInt(x));
   let lastDigit = arr.splice(0, 1)[0];
-  let sum = arr.reduce((acc,val,i) => i%2!==0 ? acc + val : acc + (val * 2) % 9 || 9,0);
+  let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + (val * 2) % 9 || 9), 0);
   sum += lastDigit;
   return sum % 10 === 0;
-}
+};
 ```
 
 ```js
-luhnCheck("4485275742308327"); // true
+luhnCheck('4485275742308327'); // true
 luhnCheck(6011329933655299); //  true
 luhnCheck(123456789); // false
 ```

tag_database

@@ -96,6 +96,7 @@ JSONToFile:node
 last:array
 lcm:math
 lowercaseKeys:object
+luhnCheck:uncategorized
 mapObject:array
 mask:string
 maxN:array