Running code or an iFrame in the messenger?

Is it possible (or: what is the best way to...) run a small bit of code or show an iFrame in the messenger?

For a certain case in a custom bot, if a user chooses a certain path, I want to show the user a quick calculator.

The code is very simple - an HTML input, and about 5 lines of javascript. Is it possible to either put the code somewhere to show it in the bot? Or otherwise, can I use an iframe that shows a page where the calculator is hosted?

Thanks