merge: optimize the countVowels algo (#886)

* pref: optimize the count vowels algo

simplify the algo by using regex and String.prototype.match method, and modified the JS Doc

* fix: resolve all requests

* pref: optimize the algo by regex

ignore the useless traverse in best case by the help of regex and String.prototype.replace method

* test: add four new test cases

* Revert "test: add four new test cases"
This reverts commit 4609833.

* style: fromat with standard js

Author: fahimfaisaal

String/CountVowels.js

@@ -1,8 +1,8 @@
 /**
  * @function countVowels
  * @description Given a string of words or phrases, count the number of vowels.
- * @param {String} url - The input string
- * @return {Number} count
+ * @param {String} str - The input string
+ * @return {Number} - The number of vowels
  * @example countVowels("ABCDE") => 2
  * @example countVowels("Hello") => 2
  */
@@ -11,15 +11,11 @@ const countVowels = (str) => {
   if (typeof str !== 'string') {
     throw new TypeError('Input should be a string')
   }
-  const vowels = new Set(['a', 'e', 'i', 'o', 'u'])
-  let count = 0
-  for (let i = 0; i < str.length; i++) {
-    const char = str[i].toLowerCase()
-    if (vowels.has(char)) {
-      count++
-    }
-  }
-  return count
+
+  const vowelRegex = /[aeiou]/gi
+  const vowelsArray = str.match(vowelRegex) || []
+
+  return vowelsArray.length
 }
 
 export { countVowels }