Coding Walkthrough #3: Encode/Decode a Message + Clean up

Video Description:

Previous video: https://www.useloom.com/share/8dfa9497fa454da99a5fe1445f22e256

Cleaned up code: https://hatchcoding.com/code/showcase/27078
Stackoverflow post: https://stackoverflow.com/questions/4467539/javascript-modulo-gives-a-negative-result-for-negative-numbers

split() documentation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split

join() documentation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join