SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<input type="checkbox" class="mySelector" value="tickOne" />
<input type="checkbox" class="mySelector" value="tickTwo" />
<input type="checkbox" class="mySelector" value="tickThree" />


<input type="hidden" id="myHiddenInput" />

JavaScript

$(".mySelector:checkbox").change(function() {
  var values = $(".mySelector:checkbox:checked").map(function() {
                 return this.value;
               }).get().join(', ');
  $("#myHiddenInput").val(values);
  alert($("#myHiddenInput").val());
});