Dart is an open-source, scalable, object-oriented programming language, with robust libraries and runtimes, for building web, server, and mobile apps. It is developed by Google,...
Clojure to JS compiler
Haxe is an open source toolkit based on a modern, high level, strictly typed programming language, a cross-compiler, a complete cross-platform standard library and ways to access...
Ceylon is a language for writing large programs in teams, with a powerful flow-sensitive static type system. It runs on the JVM or in a browser (transpiled to JS).
Smalltalk on the web.
Develop software on one of the best IDEs anywhere: Pharo, and deploy on the web. In development, but the roadmap has a very inclusive goal.
Java (via GWT)
A pythonic compile-to-js language with added sugar, pattern matching, and a powerful macro system.