Caesar cipher algorithm

Author: dhimasanb

Algorithm/caesarCipher.js

@@ -0,0 +1,31 @@
+function caesarCipher(str, num) {
+    num = num % 26;
+    let lowerCaseString = str.toLowerCase();
+    let alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('');
+    let newString = '';
+  
+    for (let i = 0; i < lowerCaseString.length; i++) {
+      let currentLetter = lowerCaseString[i];
+      if (currentLetter === ' ') {
+        newString += currentLetter;
+        continue;
+      }
+      let currentIndex = alphabet.indexOf(currentLetter);
+      let newIndex = currentIndex + num;
+      if (newIndex > 25) newIndex = newIndex - 26;
+      if (newIndex < 0) newIndex = 26 + newIndex;
+      if (str[i] === str[i].toUpperCase()) {
+        newString += alphabet[newIndex].toUpperCase();
+      }
+      else newString += alphabet[newIndex];
+    }
+  
+    return newString;
+  }
+  
+  caesarCipher('Zoo Keeper', 2); // Bqq Mggrgt
+  
+  caesarCipher('Javascript', -900); // Bqq Mggrgt
+  
+  caesarCipher('Dhimas Akbar', 27); // Eijnbt Blcbs
+