<!DOCTYPE html><html><head> ???<meta http-equiv="Content-type" content="text/html; charset=utf-8" /> ???<title></title> ???<link rel="stylesheet" href="imooc.css" type="text/css"> ???<script src="http://libs.baidu.com/jquery/1.9.1/jquery.js"></script></head><body> ???<h2>子元素筛选选择器</h2> ???<h3>:first-child、:last-child、:only-child</h3> ???<div class="left first-div"> ???????<div class="div"> ???????????<a>:first-child</a> ???????????<a>第二个元素</a> ???????????<a>:last-child</a> ???????</div> ???????<div class="div"> ???????????<a>:first-child</a> ???????</div> ???????<div class="div"> ???????????<a>:first-child</a> ???????????<a>第二个元素</a> ???????????<a>:last-child</a> ???????</div> ???</div> ???<script type="text/javascript"> ???????//查找class="first-div"下的第一个a元素 ???????//针对所有父级下的第一个 ???????$(".first-div a:first-child").css("color", "#CD00CD"); ???</script> ???<script type="text/javascript"> ???????//查找class="first-div"下的最后一个a元素 ???????//针对所有父级下的最后一个 ???????//如果只有一个元素的话，last也是第一个元素 ???????$(".first-div a:last-child").css("color", "red"); ???</script> ???<script type="text/javascript"> ???????//查找class="first-div"下的只有一个子元素的a元素 ???????$(".first-div a:only-child").css("color", "blue"); ???</script> ???<h3>:nth-child、:nth-last-child</h3> ???<div class="left last-div"> ???????<div class="div"> ???????????<a>:first-child</a> ???????????<a>第二个元素</a> ???????????<a>第三个元素</a> ???????????<a>:last-child</a> ???????</div> ???????<div class="div"> ???????????<a>:first-child</a> ???????????<a>第二个元素</a> ???????</div> ???????<div class="div"> ???????????<a>:first-child</a> ???????????<a>第二个元素</a> ???????????<a>第三个元素</a> ???????????<a>:last-child</a> ???????</div> ???</div> ???<script type="text/javascript"> ???????//查找class="last-div"下的第二个a元素 ???????$(".last-div a:nth-child(2)").css("color", "#CD00CD"); ???</script> ???<script type="text/javascript"> ???????//查找class="last-div"下的倒数第二个a元素 ???????$(".last-div a:nth-last-child(2)").css("color", "red"); ???</script></body></html>注意：
jQuery实现:nth-child(n)是严格来自CSS规范，所以n值是“索引”，也就是说，从1开始计数，:nth-child(index)从1开始的，而eq(index)是从0开始的
jQuery选择器之子元素选择器
原文地址：http://www.cnblogs.com/sunxirui00/p/7542568.html