merge: Upgrade Lower function (TheAlgorithms#894)

* docs: update the js doc * pref: Optimize algo via regex ignore the useless traverse in best case via regex and String.prototype.replace * test: add some new test cases * fix: styled with standard * refactor: remove useless variable

Author: fahimfaisaal

String/Lower.js

@@ -1,8 +1,8 @@
 /**
  * @function lower
  * @description Will convert the entire string to lowercase letters.
- * @param {String} url - The input URL string
- * @return {String} Lowercase string
+ * @param {String} str - The input string
+ * @returns {String} Lowercase string
  * @example lower("HELLO") => hello
  * @example lower("He_llo") => he_llo
  */
@@ -12,17 +12,12 @@ const lower = (str) => {
  throw new TypeError('Invalid Input Type')
  }
 
- let lowerString = ''
+ return str
+ .replace(/[A-Z]/g, (_, indexOfUpperChar) => {
+ const asciiCode = str.charCodeAt(indexOfUpperChar)
 
- for (const char of str) {
- let asciiCode = char.charCodeAt(0)
- if (asciiCode >= 65 && asciiCode <= 90) {
- asciiCode += 32
- }
- lowerString += String.fromCharCode(asciiCode)
- }
-
- return lowerString
+ return String.fromCharCode(asciiCode + 32)
+ })
 }
 
 export { lower }

String/test/Lower.test.js

@@ -1,9 +1,19 @@
 import { lower } from '../Lower'
 
-describe('Lower', () => {
- it('return uppercase strings', () => {
- expect(lower('hello')).toBe('hello')
+describe('Testing the Lower function', () => {
+ it('Test 1: Check by invalid type', () => {
+ expect(() => lower(345)).toThrowError()
+ expect(() => lower(true)).toThrowError()
+ expect(() => lower(null)).toThrowError()
+ })
+
+ it('Test 2: Check by uppercase string', () => {
  expect(lower('WORLD')).toBe('world')
- expect(lower('hello_WORLD')).toBe('hello_world')
+ expect(lower('Hello_WORLD')).toBe('hello_world')
+ })
+
+ it('Test 3: Check by lowercase string', () => {
+ expect(lower('hello')).toBe('hello')
+ expect(lower('hello_world')).toBe('hello_world')
  })
 })