To start with, just run following command

node secretMessage.js

Enter some text: e.g. "Shhh! Secret message for someone!"

Copy content returned from Script. Paste it into some file, name it with ext '.html'. And open it in Browser. Or maybe paste it in online html editor.

Some random preview will be there, no one can read it. But when we copy and paste it in nodepad, we see that hidden message!