In PHP, I use Kuwamoto's class to pluralize nouns in my strings. I didn't find something as good as this script in javascript except for some plugins. So, it would be great to have a javascript function based on Kuwamoto's class.
http://kuwamoto.org/2007/12/17/improved-pluralizing-in-php-actionscript-and-ror/
So, I answer my own question by sharing my translation in javascript of Kuwamoto's PHP class.
Easy to use:
DEMO