Improved ciphers

Ciphers/Atbash.js

@@ -1,30 +1,22 @@
-/*
-The Atbash cipher is a particular type of monoalphabetic cipher
-formed by taking the alphabet and mapping it to its reverse,
-so that the first letter becomes the last letter,
-the second letter becomes the second to last letter, and so on.
-*/
-
 /**
- * Decrypt a Atbash cipher
- * @param {String} str - string to be decrypted/encrypt
- * @return {String} decrypted/encrypted string
+ * @function Atbash - Decrypt a Atbash cipher
+ * @description - The Atbash cipher is a particular type of monoalphabetic cipher formed by taking the alphabet and mapping it to its reverse, so that the first letter becomes the last letter, the second letter becomes the second to last letter, and so on.
+ * @param {string} str - string to be decrypted/encrypt
+ * @return {string} decrypted/encrypted string
+ * @see - [wiki](https://en.wikipedia.org/wiki/Atbash)
  */
-function Atbash (message) {
-  let decodedString = ''
-  for (let i = 0; i < message.length; i++) {
-    if (/[^a-zA-Z]/.test(message[i])) {
-      decodedString += message[i]
-    } else if (message[i] === message[i].toUpperCase()) {
-      decodedString += String.fromCharCode(90 + 65 - message.charCodeAt(i))
-    } else {
-      decodedString += String.fromCharCode(122 + 97 - message.charCodeAt(i))
-    }
+const Atbash = (str) => {
+  if (typeof str !== 'string') {
+    throw new TypeError('Argument should be string')
   }
-  return decodedString
-}
 
-export { Atbash }
+  return str.replace(/[a-z]/gi, (char) => {
+    if (/[A-Z]/.test(char)) {
+      return String.fromCharCode(90 + 65 - char.charCodeAt())
+    }
+
+    return String.fromCharCode(122 + 97 - char.charCodeAt())
+  })
+}
 
-// > Atbash('HELLO WORLD')
-// 'SVOOL DLIOW'
+export default Atbash

Ciphers/test/Atbash.test.js

@@ -0,0 +1,17 @@
+import Atbash from '../Atbash'
+
+describe('Testing Atbash function', () => {
+  it('Test - 1, passing the non-string as an argument', () => {
+    expect(() => Atbash(0x345)).toThrow()
+    expect(() => Atbash(123)).toThrow()
+    expect(() => Atbash(123n)).toThrow()
+    expect(() => Atbash(false)).toThrow()
+    expect(() => Atbash({})).toThrow()
+    expect(() => Atbash([])).toThrow()
+  })
+
+  it('Test - 2, passing all alphabets', () => {
+    expect(Atbash('HELLO WORLD')).toBe('SVOOL DLIOW')
+    expect(Atbash('The quick brown fox jumps over the lazy dog')).toBe('Gsv jfrxp yildm ulc qfnkh levi gsv ozab wlt')
+  })
+})