diff --git a/Ciphers/XORCipher.js b/Ciphers/XORCipher.js
index 944081b99..d73827a2e 100644
--- a/Ciphers/XORCipher.js
+++ b/Ciphers/XORCipher.js
@@ -1,31 +1,22 @@
 /**
+ * @function XORCipher
+ * @description - Encrypt using an XOR cipher
  * The XOR cipher is a type of additive cipher.
  * Each character is bitwise XORed with the key.
  * We loop through the input string, XORing each
  * character with the key.
+ * @param {string} str - string to be encrypted
+ * @param {number} key - key for encryption
+ * @return {string} encrypted string
  */
-
-/**
- * Encrypt using an XOR cipher
- * @param {String} str - String to be encrypted
- * @param {Number} key - key for encryption
- * @return {String} encrypted string
- */
-
-function XOR (str, key) {
-  let result = ''
-  for (const elem of str) {
-    result += String.fromCharCode(elem.charCodeAt(0) ^ key)
+const XORCipher = (str, key) => {
+  if (typeof str !== 'string' || !Number.isInteger(key)) {
+    throw new TypeError('Arguments type are invalid')
   }
-  return result
+
+  return str.replace(
+    /./g, (char) => String.fromCharCode(char.charCodeAt() ^ key)
+  )
 }
 
-export { XOR }
-
-// Nb: Node REPL might not output the null char '\x00' (charcode 0)
-
-// > XOR('test string', 32)
-// 'TEST\x00STRING'
-
-// > XOR('TEST\x00STRING', 32)
-// 'test string'
+export default XORCipher
diff --git a/Ciphers/test/XORCipher.test.js b/Ciphers/test/XORCipher.test.js
new file mode 100644
index 000000000..9697fc715
--- /dev/null
+++ b/Ciphers/test/XORCipher.test.js
@@ -0,0 +1,18 @@
+import XORCipher from '../XORCipher'
+
+describe('Testing XORCipher function', () => {
+  it('Test - 1, passing a non-string as an argument', () => {
+    expect(() => XORCipher(false, 0x345)).toThrow()
+    expect(() => XORCipher(true, 123)).toThrow()
+    expect(() => XORCipher(1n, 123n)).toThrow()
+    expect(() => XORCipher(false, 0.34)).toThrow()
+    expect(() => XORCipher({})).toThrow()
+    expect(() => XORCipher([])).toThrow()
+  })
+
+  it('Test - 2, passing a string & number as an argument', () => {
+    // NB: Node REPL might not output the null char '\x00' (charcode 0)
+    expect(XORCipher('test string', 32)).toBe('TEST\x00STRING')
+    expect(XORCipher('TEST\x00STRING', 32)).toBe('test string')
+  })
+})