You can never know! That's what I'm saying. it's not like learning a new programming paradigm (like functional) that will take days or weeks, it will take 10 minutes reading www.coffeescript.org front page to see if my career advice is right or wrong. You can't call yourself a nerd without knowing the most thriving dialect of that language... Specially if you're young and reading a hacker website.

I realy don't want to get into a virtual pointless argument, but just out of curiosity: do you know CoffeeScript? Because it's very strange to me that someone might be against using CoffeeScript and condemning it like that (its debugging is worse than JS, but on every other front it's the clear winner). if you're not familiar with it, I suggest you take a look at CoffeeScript.org to see how and why it differs from JavaScript.