Good news: there is now a requests module that supports javascript: https://pypi.org/project/requests-html/
from requests_html import HTMLSession
session = HTMLSession()
r = session.get('http://www.yourjspage.com')
r.html.render() # this call executes the js in the page
As a bonus this wraps BeautifulSoup
, I think, so you can do things like
r.html.find('#myElementID').text
which returns the content of the HTML element as you’d expect.