When it comes to JavaScript / Web APIs, the language you're looking for is WebIDL. The standards specify all APIs in WebIDL, and I believe Chrome does exactly w

When it comes to JavaScript / Web APIs, the language you're looking for is WebIDL. The standards specify all APIs in WebIDL, and I believe Chrome does exactly what you're describing, generating C++ interfaces from WebIDL. In Cloudflare Workers we've taken a different path, having the C++ interfaces be the source of truth, as we feel this leads to less cognitive overhead for developers on the project (and avoided the need to write a new WebIDL code generator matching our internal C++ dialect). It's possible we'll revisit this decision in the future, but for the moment it seems to be working well.