第14行，为什么得不到想要的结果呢？
1 <!DOCTYPE html>
2 <html>
3 <head>
4 <meta charset="utf-8">
5 <meta http-equiv="X-UA-Compatible" content="IE=edge">
6 <title></title>
7 <script src="框架/jquery-2.2.0.min.js"></script>
8 <script type="text/javascript">
9 $(function() {
10 var $t_a = $(‘.test :hidden‘);
11 var $t_b = $(‘.test:hidden‘);
12 var len_a = $t_a.length;
13 var len_b = $t_b.length;
14 alert("$(‘.test :hidden‘) =" + len_a);//4,不能得到这个结果！为什么是0
15 alert("$(‘.test:hidden‘) =" + len_b);//3
16 })
17 </script>
18 </head>
19 <body>
20 <div>
21 <div style="display: none">aa</div>
22 <div style="display: none">bb</div>
23 <div style="display: none">cc</div>
24 <div class="test" style="display: none">dd</div>
25 </div>
26 <div class="test" style="display: none">ee</div>
27 <div class="test" style="display: none">ff</div>
28 </body>
29 </html>
原文：http://www.cnblogs.com/thqy39/p/5345971.html