Many years have passed, and I’m even more proud of the project that Opal has become, the maturity and the feature parity with MRI is astounding, the new features that are coming in version 1.0 are even more amazing, and the roadmap ahead makes Opal one of the best choices among compile-to-JS languages.

Source: Opal 1.0

Nice. Would like to see this gain more adoption, especially given the fragmented nature of JavaScript libraries.