It's a bit unclear what you mean when you say "what can I do". If you're referring to specific language features that are available to Java or C++ that are not available to JavaScript, it would be ...

The AOSP, which is a Linux distribution, started using Rust on new code in April 2021 but left its C/C++ code base in place. That month, AOSP also backed calls for Rust as an option for new code ...

Its top 10 were JavaScript, Python, Java, PHP, C#, CSS, C++, TypeScript, Ruby, C, and Swift. Rust was in 19th spot. Notably, though, Java was not one of the languages to see much growth on GitHub.