/**
 * Returns true if an element has a specified class name
 */
function hasClass(node, className) {
  if (node.className == className) {
    return true;
  }
  var reg = new RegExp('(^| )'+ className +'($| )')
  if (reg.test(node.className)) {
    return true;
  }
  return false;
}

/**
 * Adds a class name to an element
 */
function addClass(node, className) {
  if (hasClass(node, className)) {
    return false;
  }
  node.className += ' '+ className;
  return true;
}

/**
 * Toggles a class name on or off for an element
 */
function toggleClass(node, className) {
  if (!removeClass(node, className) && !addClass(node, className)) {
    return false;
  }
  return true;
}

/**
 * Removes a class name from an element
 */
function removeClass(node, className) {
  if (!hasClass(node, className)) {
    return false;
  }
  // Replaces words surrounded with whitespace or at a string border with a space. Prevents multiple class names from being glued together.
  node.className = eregReplace('(^|\\s+)'+ className +'($|\\s+)', ' ', node.className);
  return true;
}

/**
 * Emulate PHP's ereg_replace function in javascript
 */
function eregReplace(search, replace, subject) {
  return subject.replace(new RegExp(search,'g'), replace);
}