Ancestry 介绍
Adds two additional filter types to jQuery:
$().descendantOf(DOMElement);
$().ancestorOf(DOMElement);
This plugin was created because there is no default method for determining
DOMElement containment after initial selection. It was discussed on the jQuery
Development group and the following people contributed comments and code that
all informed the final result: Michael Geary, Diego Perini, John-David Dalton,
John Resig, and Nathan Hammond.
Also, if you’re feeling bold, there is included a bit of code to allow for a
context to be specified when searching for a DOMElement.