Im not a javascript expert so Im hoping someone here can help me figure out what i need done..
I found a javascript tutorial that im trying to implement in my script.

What works: limiting the amount of check box a user can check.

not sure how to do the following: create the javascript specific to the group of check box offered to the user so that the java script doesn't affect other checkboxs in the script.

HTML Code:
<input id="vehicle" type="checkbox" name="vehicle[]" value="Bike">bike <br />
<input id="vehicle" type="checkbox" name="vehicle[]" value="Car">car <br />
<input id="vehicle" type="checkbox" name="vehicle[]" value="van"> Van <br />
HTML Code:
<script src="http://code.jquery.com/jquery-latest.js"></script>

	<script type="text/javascript" > 
          var max = 3;
          var checkboxes = $('input[type="checkbox"]');
          var current = checkboxes.filter(':checked').length;
        checkboxes.filter(':not(:checked)').prop('disabled', current >= max);