J2CL
Java to Closure JavaScript transpiler
...The generated JavaScript is fully type-safe and can be aggressively optimized by the Closure Compiler to reduce code size and improve performance. J2CL is widely used internally at Google in large-scale applications such as Gmail and Google Docs, demonstrating its production readiness and scalability. It supports interoperability between Java and JavaScript through tools like JsInterop, enabling seamless integration of code across languages.