javascript - How to check atleast one checkbox is checked in multiple checkbox -

in form many check-box used want check atleast 1 checkbox checked

<div id="sun">     <li><?php echo $this->__("sun");?> </li>     <li><input class="allday" type="checkbox" name="availableday[sunday][9-12]" value="9am - 12am"></li>     <li><input class="allday" type="checkbox" name="availableday[sunday][12-6]" value="12pm - 6pm"></li>     <li><input class="allday" type="checkbox" name="availableday[sunday][6-9]" value="6pm - 9pm"></li> </div> <div id="mon">     <li><?php echo $this->__("mon");?> </li>     <li><input class="allday" type="checkbox" name="availableday[monday][9-12]" value="9am - 12am"></li>     <li><input class="allday" type="checkbox" name="availableday[monday][12-6]" value="12pm - 6pm"></li>     <li><input class="allday" type="checkbox" name="availableday[monday][6-9]" value="6pm - 9pm"></li> </div> <div id="tue">     <li><?php echo $this->__("tue");?> </li>     <li><input class="allday" type="checkbox" name="availableday[tuesday][9-12]" value="9am - 12am"></li>     <li><input class="allday" type="checkbox" name="availableday[tuesday][12-6]" value="12pm - 6pm"></li>     <li><input class="allday" type="checkbox" name="availableday[tuesday][6-9]" value="6pm - 9pm"></li> </div> <div id="wed">     <li><?php echo $this->__("wed");?> </li>     <li><input class="allday" type="checkbox" name="availableday[wednesday][9-12]" value="9am - 12am"></li>     <li><input class="allday" type="checkbox" name="availableday[wednesday][12-6]" value="12pm - 6pm"></li>     <li><input class="allday" type="checkbox" name="availableday[wednesday][6-9]" value="6pm - 9pm"></li> </div> 

how validate atleast 1 checkbox checked.

something along following lines:

var formnodes  = document.checks.getelementsbytagname('input'); (var i=0;i<formnodes.length;i++) {    /* if 1 true set variable true , exit loop */ } 

stack overflow post here

cheers,

truez