Stimulus is a JavaScript framework with modest ambitions. It doesn’t seek to take over your entire front-end—in fact, it’s not concerned with rendering HTML at all. Instead, it’s designed to augment your HTML with just enough behavior to make it shine. Stimulus pairs beautifully with Turbolinks to provide a complete solution for fast, compelling applications with a minimal amount of effort. modest JavaScript framework for the HTML you already have.

I’ve been playing with Stimulus since it was released, and it’s interesting. I can see this being a good answer for stuff like WordPress themes that are designed to be server side but, like any site, could benefit from client-side JavaScript enhancements.