Merge branch 'master' into master

snippets/3DigHexcode-to-6DigHexcode.md

@@ -0,0 +1,11 @@
+### 3DigHexcode to 6DigHexcode
+
+Use `Array.map()`, `split()` and `Array.join()` to join the mapped array for converting a three-digit RGB notated hexadecimal colorcode to the six-digit form. 
+
+```js
+const convertHex = shortHex => 
+  shortHex[0] == '#' ? ('#' + shortHex.slice(1).split('').map(x => x+x).join('')) : 
+    ('#' + shortHex.split('').map(x => x+x).join(''));
+// convertHex('#03f') -> '#0033ff'
+// convertHex('05a') -> '#0055aa'
+```

snippets/array-concatenation.md

@@ -1,8 +1,8 @@
 ### Array concatenation
 
-Use `Array.concat()` to concatenate an array with any additional arrays and/or values, specified in `args`.
+Use Array spread operators (`...`) to concatenate an array with any additional arrays and/or values, specified in `args`.
 
 ```js
-const ArrayConcat = (arr, ...args) => [].concat(arr, ...args); 
-// ArrayConcat([1], [1, 2, 3, [4]]) -> [1, 2, 3, [4]]
+const ArrayConcat = (arr, ...args) => [...arr,...args]; 
+// ArrayConcat([1], [1, 2, 3, [4]]) -> [1, 1, 2, 3, [4]]
 ```

snippets/array-without.md

@@ -1,9 +1,9 @@
 ### Array without
 
-Use `Array.filter()` to create an array excluding all given values.
+Use `Array.filter()` to create an array excluding(using `!Array.includes()`) all given values.
 
 ```js
-const without = (arr, ...args) => arr.filter(v => args.indexOf(v) === -1);
-// without[2, 1, 2, 3], 1, 2) -> [3]
+const without = (arr, ...args) => arr.filter(v => !args.includes(v));
+// without([2, 1, 2, 3], 1, 2) -> [3]
 // without([2, 1, 2, 3, 4, 5, 5, 5, 3, 2, 7, 7], 3, 1, 5, 2) -> [ 4, 7, 7 ]
 ```

snippets/compose-functions.md

@@ -1,6 +1,6 @@
 ### Compose functions
 
-Use `Array.reduce()` with the spread operator (`...`) to perform right-to-;eft function composition.
+Use `Array.reduce()` to perform right-to-left function composition.
 The last (rightmost) function can accept one or more arguments; the remaining functions must be unary.
 
 ```js
@@ -11,4 +11,4 @@ const multiply = (x, y) => x * y
 const multiplyAndAdd5 = compose(add5, multiply)
 multiplyAndAdd5(5, 2) -> 15
 */
-```
+```

snippets/initialize-array-with-range.md

@@ -5,6 +5,6 @@ You can omit `start` to use a default value of `0`.
 
 ```js
 const initializeArrayRange = (end, start = 0) =>
-  Array.apply(null, Array(end - start)).map((v, i) => i + start);
+  Array.from({ length: end - start }).map((v, i) => i + start)
 // initializeArrayRange(5) -> [0,1,2,3,4]
 ```

snippets/read-file-to-array.md

@@ -0,0 +1,19 @@
+### Read a file to an Array
+
+Use `readFileSync` function in `fs` node package to create a `Buffer` from a file.
+convert buffer to string using `toString(encoding)` function.
+creating an array from contents of file by `split`ing file content line by line(each `\n`).
+
+  ```js
+const fs = require('fs');
+const readFileToArray = filename => fs.readFileSync(filename).toString('UTF8').split('\n');
+/*
+  contents of test.txt :
+    line1
+    line2
+    line3
+    ___________________________
+  let arr = readFileToArray('test.txt')
+  console.log(arr) // -> ['line1', 'line2', 'line3']
+ */
+```

snippets/take-every-nth-element.md

@@ -0,0 +1,8 @@
+### Take every nth element of an array
+
+Use `Array.filter()` to create a new array that contains every nth element of a given array.
+
+```js
+const everynth = (arr, nth) => arr.filter((e, i) => i % nth === 0);
+// everynth([1,2,3,4,5,6], 2) -> [ 1, 3, 5 ]
+```

snippets/write-json-to-file.md

@@ -1,4 +1,4 @@
-### Write a JSON to a file
+### Write JSON to file
 
 Use `fs.writeFile()`, template literals and `JSON.stringify()` to write a `json` object to a `.json` file.