Monoalphabetic substitution - HTML/JS

Tiny tool to do monoalphabetic substitution. Text can be added to the plaintext area or the encrypted text area. Substitutions are then added in the designated fields. The text can be decrypted or encrypted by a press on the buttons. WARNING: Encryption en decryption override the textarea on the other side.

To accommodate easy trial and error the text being encrypted/decrypted will always be in lower case. The (currently) unedited output will appear as a capital, while the substituted characters will appear in lower case as well.