From b898a00a221e6b69f5dff131ecc45206de3bb88c Mon Sep 17 00:00:00 2001
From: alex_p <aleksborislavskij@gmail.com>
Date: Mon, 31 Oct 2022 22:03:40 +0300
Subject: [PATCH 1/2] algorithm: add PercentageOfLetters algo and a test for it

---
 String/PercentageOfLetters.js           | 28 +++++++++++++++++++++++++
 String/test/PercentageOfLetters.test.js | 16 ++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 String/PercentageOfLetters.js
 create mode 100644 String/test/PercentageOfLetters.test.js

diff --git a/String/PercentageOfLetters.js b/String/PercentageOfLetters.js
new file mode 100644
index 0000000000..a22a7ae08e
--- /dev/null
+++ b/String/PercentageOfLetters.js
@@ -0,0 +1,28 @@
+/**
+ * @function percentageOfLetter
+ * @description Return the percentage of characters in 'str'
+ * that equal 'letter' rounded down to the nearest whole percent.
+ * More info: https://leetcode.com/problems/percentage-of-letter-in-string/
+ * @param {String} str
+ * @param {String} letter
+ * @returns {Number}
+ * @example
+ * const str = 'foobar', const letter = 'o'
+ * percentageOfLetter(str, letter) // ===> 33
+ */
+const percentageOfLetter = (str, letter) => {
+  if (typeof str !== 'string' || typeof letter !== 'string') {
+    throw new Error('Input data must be strings')
+  }
+  let letterCount = 0
+  // Iterate through the whole given text
+  for (let i = 0; i < str.length; i++) {
+    // Count how often the letter appears in the word
+    letterCount = str[i].toLowerCase() === letter.toLowerCase() ? letterCount + 1 : letterCount + 0
+  }
+  const percentage = Math.floor((100 * letterCount) / str.length)
+
+  return percentage
+}
+
+export { percentageOfLetter }
diff --git a/String/test/PercentageOfLetters.test.js b/String/test/PercentageOfLetters.test.js
new file mode 100644
index 0000000000..7a58dd0ecc
--- /dev/null
+++ b/String/test/PercentageOfLetters.test.js
@@ -0,0 +1,16 @@
+import { percentageOfLetter } from '../PercentageOfLetters'
+
+describe('Percentage of Letters in a String', () => {
+  test('Calculate percent for lower case', () => {
+    expect(percentageOfLetter('foobar', 'o')).toEqual(33)
+    expect(percentageOfLetter('aaabcd', 'a')).toEqual(50)
+  })
+  test('Calculate percent for upper case', () => {
+    expect(percentageOfLetter('foobar', 'o')).toEqual(33)
+    expect(percentageOfLetter('aAabcd', 'a')).toEqual(50)
+  })
+  test('Throwing an exception', () => {
+    expect(() => percentageOfLetter(100, 'string')).toThrow()
+    expect(() => percentageOfLetter('string', true)).toThrow()
+  })
+})

From 06992e0021eaa4595b7be330254e07dfd6b4ee35 Mon Sep 17 00:00:00 2001
From: alex_p <aleksborislavskij@gmail.com>
Date: Mon, 31 Oct 2022 22:41:15 +0300
Subject: [PATCH 2/2] refactor: remove empty line

---
 String/PercentageOfLetters.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/String/PercentageOfLetters.js b/String/PercentageOfLetters.js
index a22a7ae08e..fbd6a03be3 100644
--- a/String/PercentageOfLetters.js
+++ b/String/PercentageOfLetters.js
@@ -18,10 +18,9 @@ const percentageOfLetter = (str, letter) => {
   // Iterate through the whole given text
   for (let i = 0; i < str.length; i++) {
     // Count how often the letter appears in the word
-    letterCount = str[i].toLowerCase() === letter.toLowerCase() ? letterCount + 1 : letterCount + 0
+    letterCount += str[i].toLowerCase() === letter.toLowerCase() ? 1 : 0
   }
   const percentage = Math.floor((100 * letterCount) / str.length)
-
   return percentage
 }