I wish to first submit a post request and move to different page in flask

Requirement:

How do I call a python function recommender.py in javascript? I am trying to link a function in python to be used in my script.js on button click

I have a file recommender.py, which contains a python function get_recommendations(title)
I want to use this in my script.js file

Flask route with send_file function called via ajax-request

My problem is almost exactly like in this unsolved quastion.