feat(revstring): Add revstring function (#99)

Closes #98

Author: mfuellbier

src/index.js

@@ -1,3 +1,4 @@
+import revstring from './revstring'
 import initArray from './init-array'
 import reduce from './reduce-to-tally'
 import flatten from './flatten'
@@ -34,6 +35,7 @@ import round from './round'
 import checkPalindrome from './checkPalindrome'
 
 export {
+  revstring,
   initArray,
   reduce,
   flatten,

src/revstring.js

@@ -0,0 +1,18 @@
+export default revstring
+
+/**
+ * Original Source: https://stackoverflow.com/a/35211814
+ *
+ * This method will revers the order of a the chars in a string.
+ *
+ * @param {String} str - string whose order to be reversed
+ * @returns {String} - string with reversed order
+ */
+
+function revstring(str) {
+  let newString = ''
+  for (let i = str.length; i >= 0; i--) {
+    newString += str.charAt(i)
+  }
+  return newString
+}

test/revstring.test.js

@@ -0,0 +1,16 @@
+import test from 'ava'
+import {revstring} from '../src'
+
+test('string with only letters', t => {
+  const str = "abcdefG"
+  const expected = "Gfedcba"
+  const result = revstring(str)
+  t.is(expected, result)
+})
+
+test('string with letters and special characters', t => {
+  const str = 'abc!"§'
+  const expected = '§"!cba'
+  const result = revstring(str)
+  t.is(expected, result)
+})