find() 方法获得当前元素集合中每个元素的后代，通过选择器、jQuery 对象或元素来筛选。
<!DOCTYPE html> <html> <head> <script type="text/javascript" src="/jquery/jquery.js"></script> </head> <body> <ul class="level-1"> <li class="item-i">I</li> <li class="item-ii">II <ul class="level-2"> <li class="item-a">A</li> <li class="item-b">B <ul class="level-3"> <li class="item-1">1</li> <li class="item-2">2</li> <li class="item-3">3</li> </ul> </li> <li class="item-c">C</li> </ul> </li> <li class="item-iii">III</li> </ul> <script> $('li.item-ii').find('li').css('background-color', 'red'); </script> </body> </html>
