About a year a ago, started from scratch writing a front-end client SPA for web-based software -- it's a custom framework built around Backbone.js and jQuery, written in CoffeeScript. The .coffee files are beautiful, and on save a shell script automatically compiles all the .coffee files down to a single JavaScript file that I would describe as good JavaScript code.
Not open source, so no demo, but it's definitely possible to create good JS.
Not open source, so no demo, but it's definitely possible to create good JS.