Get All checked-Checkbox whose ID ~ start with "email_"

get all checked CheckBox whose id start with "email_"

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js">

</script>

<script>

    $(document).ready(function () {

        $("button").click(function () {

           $('input[id^="email_"]:checked').each(function () {    
               alert($(this).attr('id'));
           });

        });

    });

</script>

----- This should be in header portion of a page And As you see this is done by the Jquery :)