I wrote the user-interface for my iPad app in JS (using PhoneGap) initially. Working on a large pure JS UI project sure makes you realize the shortcomings of JS, both fundamental and syntactic. It took a week to convert the JS to CS by hand and I did it hoping that the one-time effort would pay itself off over the next few months of development. Within just 2 weeks after the conversion, I started cranking out more features than I had in months before, and surprisingly with very little new code being written.

CS enabled me to write cleaner, simpler code in 5 lines instead of 30 lines in JS. While I don't care about the LOC as a metric of performance, I do have a limited short-term memory and can't remember the intricate workings of a class I wrote 2 months ago. Being able to recollect how a class functions is significantly easier if you have to read 50 LOC instead of 300.

I don't understand why people worry about being pro or against a language or a variant. Before CS, I managed to write decent JS that made me productive. With CS, I write better code and am more productive. Hence I continue to use CS. YMMV.

Also it's amusing to see this was posted to HN by jashkenas himself.