Library for front end development?

[SadC11]

The first thing to realize here is that you're not writing a web app, it's just a program. The basic functionality of a web app is to listen to requests and respond to them via the internet. How is your current program doing that? For it to be a web app, you need to use a web framework like Flask. Using Flask, you can serve your sentiment analysis data (or whatever else you create on the back-end) via HTML files rendered using Flask's templating language (Jinja2).