Using javascript/jquery, how to validate if at least 1 checkbox in spring's form:checkboxes is checked?

I am using spring's tag in my html. My jsp has a group of checkbox which renders value from model object "allTimeslots". This object has list of string.

    form:checkboxes element="li" path="timeslotId" id="checkbox" type="checkbox"
                                            items="${allTimeslots}" /></td></tr></table>

Now, my requirement is to check if atleast one check-box is checked when the form is submitted. I am using jquery validation where this check has to be done. I cannot use type="checkbox" as this is not permitted in spring's tag. Please suggest.