jQuery .next() gets the immediately following sibling of each element in the set of matched elements; Also check jQuery .prev();
js:
$('.target').next()
.css('background-color', 'yellow')
.append(' <span class="label label-info">next after .target</span>');
$('li').next('.target')
.css('background-color', 'yellow')
.append(' <span class="label">next with .target class</span>');
html:
<ul> <li>list item <ul> <li>list item</li> <li class="target">list item with target class</li> <li>list item</li> <li>list item</li> </ul> </li> <li>list item</li> <li class="target">list item with target class</li> <li>list item</li> <li>list item</li> </ul>