Opal is a ruby to javascript compiler. Opal includes a compiler which can be run in any browser, a corelib and runtime implementation. The corelib/runtime is also very small with the size of 10.8kb gzipped. Opal-jquery provides DOM access to opal by wrapping jQuery (or zepto) and providing a nice ruby syntax for dealing with jQuery instances as well.

Opal is a source-to-source compiler, so there is no VM as such and the compiled code aims to be as fast and efficient as possible, mapping directly to underlying javascript features and objects where possible. Opal is hosted on github and free for download.

Requirements: -
Demo: http://opalrb.org/
License: License Free