Overhead of calling into JS from Wasm is very low; DOM calls are no problem since the DOM call itself is much slower than the overhead of switching from Wasm to JS. See e.g. this article from ~4 years ago: https://hacks.mozilla.org/2018/10/calls-between-javascript-a...
There are even some libraries that try to mimic React directly from Rust, such as https://yew.rs/ (though in my experience they can be a bit harder to use than Zaplib, since they require you to learn about traits, closures, etc, and tend to also run into borrow checker issues more often -- all of those are things we try to avoid having to learn in Zaplib!)
There are even some libraries that try to mimic React directly from Rust, such as https://yew.rs/ (though in my experience they can be a bit harder to use than Zaplib, since they require you to learn about traits, closures, etc, and tend to also run into borrow checker issues more often -- all of those are things we try to avoid having to learn in Zaplib!)