Nowadays there are a lot of languages that are able to compile to JS (e.g. Dart, TypeScript, Java/GWT etc.). One that is less well-known, but will surely blow your mind, is Haxe. It is one of the earliest languages that target JS (since 2006). It is a statically-typed language with ECMAScript like syntax.
The Haxe compiler outputs lightweight, well-optimized JS code. Besides JS, it compiles to 8 other targets, which are Java, C#, PHP, C++, Python, Flash (AS3 and SWF), and Neko.
In this talk, Andy will introduce Haxe with a focus on its JS target. He will compare Haxe with JS, as well as other compile-to-JS languages. He will analyze why Haxe is able to provide portability, better run-time performance, and a more maintainable code base all at once.