In this way, adding, removing, or changing your frontend framework becomes much simpler. They had a more straightforward role in your system ("when user interacts with X call module Y.foo") instead of housing most of your code, and potentially losing all that code when you start from scratch or decide to try a different framework.
Secondly, get a better idea of what your needs are. Do you just need a few UI interactions? Is it going to be heavy on state? Do you need to run a lot of AJAX requests and update the UI accordingly? Before you can know which JS framework you need, you need to know what role the JS plays in your system. If you don't do that, every framework is a potential valid answer, since the question is too vaguely defined.