For me there is no worst thing in CS. The thing that bothers me now is that there is no practical standard on documenting the code similar to JsDoc. Yes there are a couple of ways to do that, but in fact meta-programming helps not only for cleaner code, but also Closure Compiler, any IDEs ( WebStorm autocomplete ) and also it helps make the code more readable. Anyway in every project that I work I usually try to convince my team to switch to CoffeeScript.

Big thanks to jashkenas, because ... CS is awesome!