old_contents: // get elements by class name
  
  function getClass(name)
  {
      return document.getElementsByClassName(name);
  }
new_contents: // get elements by class name
  
  function getClass(name, node)
  {
      // if node !== null && node >= 0 (is integer)
      // return document.getElementsByClassName(name)[node];
      return document.getElementsByClassName(name);
  }
subject: update to getClass()