I don’t think it’s really possible to have a system to write UI entirely in python AND use any javascript library without the whole thing being a bit of a mess. Javascript just fundamentally works quite differently from python and I think the only way to bridge the two is to build bespoke javascript designed to work with a specific python backend. You can check out Bokeh for an example of this in action. I think we have to accept the language of the web-browser is Javascript.

What might be more feasible is to bring some of the power of modern web rendering engines to python and build up an ecosystem of native python libraries (which may effectively by ports of the best of javascript). There’s this https://www.reddit.com/r/rust/comments/4gl8kx/servovdom/ project that could allow the new Servo engine to act as a powerful rendering and layout component for Python.