Added new algoritm (#433)

String/CheckVowels.js

@@ -0,0 +1,21 @@
+/*
+  Given a string of words or phrases, count the number of vowels.
+  Example: input = "hello world" return 3
+ */
+
+const checkVowels = (value) => {
+  if (typeof value !== 'string') {
+    throw new TypeError('The first param should be a string')
+  }
+  const vowels = ['a', 'e', 'i', 'o', 'u']
+  let countVowels = 0
+  for (let i = 0; i < value.length; i++) {
+    const char = value[i].toLowerCase()
+    if (vowels.includes(char)) {
+      countVowels++
+    }
+  }
+  return countVowels
+}
+
+export { checkVowels }

String/CheckVowels.test.js

@@ -0,0 +1,12 @@
+import { checkVowels } from './CheckVowels'
+
+describe('Test the checkVowels function', () => {
+  it('expect throws on use wrong param', () => {
+    expect(() => checkVowels(0)).toThrow()
+  })
+  it('count the vowels in a string', () => {
+    const value = 'Mad World'
+    const countVowels = checkVowels(value)
+    expect(countVowels).toBe(2)
+  })
+})