Reorder CORS tutorial ranking using drag and drop

cors.user.js

// ==UserScript==
// @name        CORS Tutorial Reordering
// @namespace   yijiang
// @description Reorder CORS tutorial ranking using drag and drop
// @include     https://myaces.nus.edu.sg/cors/RankTutorialServlet
// @require     https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js
// @require     https://ajax.googleapis.com/ajax/libs/jqueryui/1.11.4/jquery-ui.min.js
// @version     1
// @grant       none
// ==/UserScript==

$('form[name="FrmRankClass"] table').sortable({
  items: 'tr.tablerecord', 
  update: function(){
    $('form[name="FrmRankClass"] table tr.tablerecord').each(function(i) {
      $(this).find('select option:nth-child(' + (i+1) + ')').prop('selected', true);
    }); 
  }, 
});