I'm trying to ensure that at least one checkbox is selected.  I'm using the query validate plugin.

here is the checkbox html

1.  <!-- Checkbox -->
2. <div class="control-group">
3. <label class="control-label" for="checkboxes">Checkboxes</label>
4. <div class="controls">
5. <input type="checkbox" name="checkboxes[]" id='checkboxes' value="Students">Students<br>
6.      <input type="checkbox" name="checkboxes[]" id='checkboxes' value="Alumni">Alumni<br>
7.      <input type="checkbox" name="checkboxes[]" id='checkboxes' value="Business">Business<br>
8.      <input type="checkbox" name="checkboxes[]" id='checkboxes' value="Faculty">Faculty<br>
9. </div><!-- close controls -->
10. </div> <!-- close control group -->

Here is my js

1. $(document).ready(function(){
2. 
   
3. // Validate
4. // http://bassistance.de/jquery-plugins/jquery-plugin-validation/
5. // http://docs.jquery.com/Plugins/Validation/
6. // http://docs.jquery.com/Plugins/Validation/validate#toptions
8. $('#contact-form').validate({
9.    rules: {
10.       
11.      name: {
12.        minlength: 2,
13.        required: true
14.      },
15.       
16.      email: {
17.        required: true,
18.        email: true
19.      },
20.       
21.      subject: {
22.       minlength: 2,
23.        required: true
24.      },
25.       
26.      message: {
27.        minlength: 2,
28.        required: true
29.      },
30. 
    
31.      select: {
32.         
33.        required: true
34.      },
35. 
    
36.      password: { 
37.                 required: true, 
38.                 minlength: 5 
39.             }, 
40.       
41.      password_confirm: { 
42.            required: true, 
43.            minlength: 5, 
44.            equalTo: "#password" 
45.        },
46. 
    
47.           checkboxes: { 
48.            //required: true,
49.            //minlength: 1
50.             required: function(elem)
51.             {
52.                 return $("input.select:checked").length > 0;
53.             }
54.              
55.           }
56.    },
57.    messages: { 
58.             name: "Enter your name",
59. 
    
60.             password: { 
61.                 required: "Provide a password", 
62.                 rangelength: jQuery.format("Enter at least {0} characters") 
63.             },
64. 
    
65.             password_confirm: { 
66.                 required: "Repeat your password", 
67.                 minlength: jQuery.format("Enter at least {0} characters"), 
68.                 equalTo: "Enter the same password as above" 
69.             }, 
70. 
    
71.             email: { 
72.                 required: "Please enter a valid email address", 
73.                 minlength: "Please enter a valid email address", 
74.                 remote: jQuery.format("{0} is already in use") 
75.             },   
76.             
77.         },
78.    highlight: function(label) {
79.     $(label).closest('.control-group').addClass('error');
80.    },
81.    success: function(label) {
82.     label
83.     .text('OK!').addClass('valid')
84.     .closest('.control-group').addClass('success');
85.    }
86.      
87.  });
88.   
89. }); // end document.ready

I was trying to keep it as simple as possible and found this example here on site point but it doesn't seem to work how i'm using it. Also i have tried it with and without the array[] added onto the checkboxes. I'm using the [] to process it on the php side

1. checkboxes: { 
2.           
3.             required: function(elem)
4.             {
5.                 return $("input.select:checked").length > 0;
6.             }
7.              
8. }