代码如下：
<html>
<head>
<style>
body { font-size:16px; font-weight:bolder; }
span { color:blue; }
p { margin:5px 0; }
</style>
<script src="jquery-1.4.2.min.js"></script>
</head>
<body>
<div class="content">
<div class="current">asdf</div>
<div class="">asdf</div>
<div class="">sdf</div>
<div class="">sdf</div>
</div> <div>And One Last <span>Time</span> (most text directly in a div)</div>
<script>$(".content").children().attr("class","current");//加入jqery代码访问”<div class="">sdf</div>“节点
$(".current").css("border-bottom", "3px double red");
</script>
</body>
</html>
<html>
<head>
<style>
body { font-size:16px; font-weight:bolder; }
span { color:blue; }
p { margin:5px 0; }
</style>
<script src="jquery-1.4.2.min.js"></script>
</head>
<body>
<div class="content">
<div class="current">asdf</div>
<div class="">asdf</div>
<div class="">sdf</div>
<div class="">sdf</div>
</div> <div>And One Last <span>Time</span> (most text directly in a div)</div>
<script>$(".content").children().attr("class","current");//加入jqery代码访问”<div class="">sdf</div>“节点
$(".current").css("border-bottom", "3px double red");
</script>
</body>
</html>
$(".content").children().attr("class","current");//加入jqery代码访问”<div class="">sdf</div>“节点
$(".current").css({"border-bottom":"3px double red"});
<div class="">asdf</div>
<div class="">sdf</div>
<div class="">sdf</div>
$("div[class='']").each(function () {alert($(this).text());});