Since cyclomatic complexity is evaluated counting the number of keyword
"if, switch, while for break" etc.. every tools that works with C will do the job, like
sourcemonitor:
http://www.campwoodsw.com/sourcemonitor.html
Actually, on javascript the more you try to modulize your code, the more you will slow it down, so take it with a grain of salt ;)
EDIT:
I Really can't understand what's going on on this answer, I get another downvote, when in my answer I tell a good tool for calculating cyclomatic complexity in javascript,
and this in particular works very well.
For the second assertion, mine is a comment that comes from experience, I never tell don't modulize your js code, I only tell to make attention in doing it, because often there is a tradeoff with speed, and when I talk of speed I mean that 2 different slowdown can happen: at download time and at execution time (and in slow device like pda/smartphone this is important).
Since tools like this often drive developer into writing more code trying to chase the smaller index possible,
but in js more code unfortunately means that slowdowns can happen, and the overuse of these tools is bad.
Surelly these tools can give you hints of where your code can be improved, but you've to master how to use the tool and not blindy rely on it.
So if you downvote me again, please write a comment in which you explain why you do so, the discussion can only benefit from this, thank you and sorry for the vent.