// Copyright July 2011 Transmogrifier E-Solutions
function has_class (node, class_name) {
  var match = node.className.match ('(^| )' + class_name + '($| )');
  return match;
}

function add_class (node, class_name) {
  if (node.className == '') {
    node.className = class_name;
  } else if (!has_class (node, class_name)) {
    node.className += ' ' + class_name;
  }
}

function rem_class (node, class_name) {
  node.className = node.className.replace (new RegExp('^ *' + class_name + ' *'), '')
  node.className = node.className.replace (new RegExp(' +' + class_name + ' +', 'g'), ' ');
  node.className = node.className.replace (new RegExp(' +' + class_name + '$'), '');
}