diff --git a/String/ReverseString.js b/String/ReverseString.js
index b0342e5a61..5ced8b35cf 100644
--- a/String/ReverseString.js
+++ b/String/ReverseString.js
@@ -6,8 +6,22 @@
 /**
  * Create a new string and append
  * @complexity O(n)
+ *
+ *  Doctests
+ *
+ * > ReverseStringIterative('some')
+ *  'emos'
+ * > ReverseStringIterative('string')
+ *  'gnirts'
+ * > ReverseStringIterative('The Algorithms Javascript')
+ *  'tpircsavaJ smhtiroglA ehT'
+ * > ReverseStringIterative([])
+ *  ! TypeError
+ * > ReverseStringIterative({})
+ *  ! TypeError
+ * > ReverseStringIterative(null)
+ *  ! TypeError
  */
-
 function ReverseStringIterative (string) {
   if (typeof string !== 'string') {
     throw new TypeError('The given value is not a string')
@@ -25,11 +39,25 @@ function ReverseStringIterative (string) {
 /**
  * JS disallows string mutation so we're actually a bit slower.
  *
- * @complexity: O(n)
+ * @complexity O(n)
  *
  * 'some' -> 'eoms' -> 'emos'
+ *
+ *  Doctests
+ *
+ * > ReverseStringIterativeInplace('some')
+ *  'emos'
+ * > ReverseStringIterativeInplace('string')
+ *  'gnirts'
+ * > ReverseStringIterativeInplace('The Algorithms Javascript')
+ *  'tpircsavaJ smhtiroglA ehT'
+ * > ReverseStringIterativeInplace([])
+ *  ! TypeError
+ * > ReverseStringIterativeInplace({})
+ *  ! TypeError
+ * > ReverseStringIterativeInplace(null)
+ *  ! TypeError
  */
-
 function ReverseStringIterativeInplace (string) {
   if (typeof string !== 'string') {
     throw new TypeError('The given value is not a string')