[oneeyedpigeon]

Definitely more than zero. It's not just a case of javascript being disabled, either - there are many other reasons why it might be "unavailable", which is why I used that word.

Of course I'm not suggesting you're not allowed to use any javascript on your site, or even that you should only use it when it's strictly necessary, but if it's entirely unnecessary and you don't engage in best practise by, for example, using progressive enhancement, then that's something that could be improved.