I have may years of experience in the Frontend, where was an Ember.js contributor and Ember-Data core team member. I am doing Elixir since 2017 in my side projects.
I don’t see JS as something to be avoided but instead see it as a perfect fit to leverage the power of Elixir / Phoenix using Channels and Hooks to make web applications native to the Browser (PWA, Offline support, Web API’s like Passkey and so on)