前台代码：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="TestClassSelector.aspx.cs" Inherits="WebApplication1.TestClassSelector" %> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> <script src="Scripts/jquery-1.9.0.min.js"></script> <style type="text/css"> .first_div { background-color:red; } .second_div { background-color:green; } .first_span { 500px; height:100px; } .eric_sun_class { font-family:Arial; font-size:18px; } </style> </head> <body> <form id="form1" runat="server"> <div> <div class="first_div"> This is the first div </div> <div class="second_div"> This is the second div </div> <div class="first_div"> <span class="first_span"> This is the first span </span> </div> <span class="first_span eric_sun_class"> This is the first span + eric sun class. </span> <br /> <span class="eric_sun_class"> This is the eric sun class. </span> <br /> <input type="button" value="Test" onclick="btn_Click();" /> </div> </form> </body> </html> <script type="text/javascript"> function btn_Click() { alert($(".first_div").text()); alert($(".first_div.first_span").text()); } </script>
$(".first_div, .first_span")
将包含有.first_div 或者 .first_span" 的对象都取到。 这里取到 4 个 对象。
此处的Html对应
<div class="first_div"> This is the first div </div> <div class="first_div"> <span class="first_span"> This is the first span </span> </div> <span class="first_span eric_sun_class"> This is the first span + eric sun class. </span>
$(".first_div .first_span")
将以 .first_div 为类的控件 下的 以 .first_span 为类 的对象取到（类与类之间带有空格 逐层取）。 这里只取到 1 个。
对应的 className="first_span" 此处的Html对应
<div class="first_div">
<span class="first_span">
This is the first span
</span>
</div>
$(".first_span.eric_sun_class")
将包含有.first_span 并且同时包含有 .eric_sun_class 类的 对象取到（类与类之间没有空格 类似于 ‘与’ 操作）。 这里只取到1个。
对应的 className="first_span eric_sun_class" 此处的Html 对应
<span class="first_span eric_sun_class"> This is the first span + eric sun class. </span>
更多关于选择器的知识请看：