<script type="text/javascript" charset="utf-8">
 
  $(document).on('ready pjax:scriptcomplete',function(){
    // Identify this question
    var qID = {QID};
    var thisQuestion = $('#question'+qID);
 
    // A function to shuffle elements or contents of arrays
    (function($){
      $.fn.shuffle = function() {
        return this.each(function(){
          var items = $(this).children();
          return (items.length)
            ? $(this).html($.shuffle(items))
            : this;
        });
      }
 
      $.shuffle = function(arr) {
        for(
          var j, x, i = arr.length; i;
          j = parseInt(Math.random() * i),
          x = arr[--i], arr[i] = arr[j], arr[j] = x
        );
        return arr;
 
      }
    })(jQuery);
 
    // Build an array of codes of all visible sub-questions
    var sqCodes = [];
    $('li.answer-item:not(.ls-irrelevant)', thisQuestion).each(function(i) {
      var thisCode = $(this).attr('id').split('X'+qID)[1];
      sqCodes.push(thisCode);
    });
 
    // Shuffle the sub-question codes array
    sqCodes = $.shuffle(sqCodes);
 
    // Check the first two sub-question codes
    $('input[type="checkbox"][id$="X'+qID+sqCodes[0]+'"]', thisQuestion).prop('checked', true);
    $('input[type="checkbox"][id$="X'+qID+sqCodes[0]+'"]', thisQuestion).nextAll('input:hidden:eq(0)').val('Y');
    $('input[type="checkbox"][id$="X'+qID+sqCodes[1]+'"]', thisQuestion).prop('checked', true);
    $('input[type="checkbox"][id$="X'+qID+sqCodes[1]+'"]', thisQuestion).nextAll('input:hidden:eq(0)').val('Y');
  });  
</script>