前台代碼：
<%@ 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 { width: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")
將包含有.first_div 或者 .first_span" 的對象都取到。 這里取到 4 個 對象。
此處的Html對應
<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")
將以 .first_div 為類的控件 下的 以 .first_span 為類 的對象取到（類與類之間帶有空格 逐層取）。 這里只取到 1 個。
對應的 className="first_span" 此處的Html對應
<div class="first_div">
<span class="first_span">
This is the first span
</span>
</div>
$(".first_span.eric_sun_class")
將包含有.first_span 並且同時包含有 .eric_sun_class 類的 對象取到（類與類之間沒有空格 類似於 ‘與’ 操作）。 這里只取到1個。
對應的 className="first_span eric_sun_class" 此處的Html 對應
<span class="first_span eric_sun_class"> This is the first span + eric sun class. </span>
更多關於選擇器的知識請看：
http://developer.51cto.com/art/201009/226852.htm
http://www.w3.org/TR/css3-selectors/