Native libraries are hard in Rust; the compiler offers no guarantees about the memory representation of structs; or these structs needs to be FFI-Friendly with unsafe extern "C". There is no sandboxing, so a malicious code could promise the machine; or corrupt the memory silently.
Finally, dynamic library plugins are distributed as compiled code.It's easier to hide backdoors in compiled code. It's also harder to share the code than simple scripts.

There are two main ways to embed JavaScript in a Rust program. The first one is with bindings for the lightweight QuickJS engine, such as rquickjs. Take a look at AWS' LLRT (Low Latency Runtime) for an advanced integration of QuickJS in Rust.

Ho, and did I mention that QuickJS is lightweight? Around 210 KiB of code vs around 40 MiB of code for V8, all while being fast enough for most situations.

My vision of programming is to limit ourselves to two programming languages. A very powerful, secure and fast compiled language for the lower levels of the computing stack, Rust, and a less powerful and slower scripting language for high-level scripting and user interfaces, JavaScript.

Another alternative is WASM. The provided code is already compiled; and the author judges the ecosystem too immature.

The last method is the less powerful: expression engine. It allows to specify a language with some rules, even if it is not turing complete and the result always evaluate to an expression.

So to rank them:

• scripting language
• expression engine
• WASM
• at the end native libraries