setClass 介绍
Add a set of classes to elements depending on a filter. The most current use
is to append icons to links depending on domain or file type of the link, by
example. But could also help to automate styling.
The plugins allow the use of predefined set of rules (class/filter pairs) that
automatically add style to some elements includings links to docs (pdf, doc,
txt); archives (zip, rar gz) or google pages.