fcc-caesars-cipher

Project "Palindrome Checker" from FreeCodeCamp JavaScript Algorithm and Data Structures Certification URL: https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/caesars-cipher

Caesars Cipher

One of the simplest and most widely known ciphers is a Caesar cipher, also known as a shift cipher. In a shift cipher the meanings of the letters are shifted by some set amount.

A common modern use is the ROT13 cipher, where the values of the letters are shifted by 13 places. Thus A ↔ N, B ↔ O and so on.

Write a function which takes a ROT13 encoded string as input and returns a decoded string.

All letters will be uppercase. Do not transform any non-alphabetic character (i.e. spaces, punctuation), but do pass them on.

testcases from project description

• rot13("SERR PBQR PNZC") should decode to the string FREE CODE CAMP
• rot13("SERR CVMMN!") should decode to the string FREE PIZZA!
• rot13("SERR YBIR?") should decode to the string FREE LOVE?
• rot13("GUR DHVPX OEBJA SBK WHZCF BIRE GUR YNML QBT.") should decode to the string THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG.