How to validate a form with multiple checkboxes to have atleast one checked

Question

I'm trying to validate a form using the validate plugin for jquery. I want to require that the user check at least one checkbox in a group in order for the form to be submitted. Here's my jquery code:

$().ready(function() { $("#subscribeForm").validate({    rules:   { list: {required: "#list0:checked"} },    messages:  { list:  "Please select at least one newsletter"}                                                          });  }); 

and here's the html form:

<form action="" method="GET" id="subscribeForm"> <fieldset id="cbgroup">     <div><input name="list" id="list0" type="checkbox"  value="newsletter0" >zero</div>     <div><input name="list" id="list1" type="checkbox"  value="newsletter1" >one</div>     <div><input name="list" id="list2" type="checkbox"  value="newsletter2" >two</div> </fieldset> <input name="submit" type="submit"  value="submit"> 

The problem is that the form submits even if nothing is checked. How can I resolve this?

Answer 1

  $('#subscribeForm').validate( {       rules: {           list: {               required: true,               minlength: 1           }        }    }); 

I think this will make sure at least one is checked.

Answer 2

This script below should put you on the right track perhaps?

You can keep this html the same (though I changed the method to POST):

<form method="POST" id="subscribeForm">     <fieldset id="cbgroup">         <div><input name="list" id="list0" type="checkbox"  value="newsletter0" >zero</div>         <div><input name="list" id="list1" type="checkbox"  value="newsletter1" >one</div>         <div><input name="list" id="list2" type="checkbox"  value="newsletter2" >two</div>     </fieldset>     <input name="submit" type="submit"  value="submit"> </form> 

and this javascript validates

function onSubmit()  {      var fields = $("input[name='list']").serializeArray();      if (fields.length === 0)      {          alert('nothing selected');          // cancel submit         return false;     }      else      {          alert(fields.length + " items selected");      } }  // register event on form, not submit button $('#subscribeForm').submit(onSubmit) 

and you can find a working example of it here

UPDATE (Oct 2012)
Additionally it should be noted that the checkboxes must have a "name" property, or else they will not be added to the array. Only having "id" will not work.

UPDATE (May 2013)
Moved the submit registration to javascript and registered the submit onto the form (as it should have been originally)

UPDATE (June 2016)
Changes == to ===