function hasClass(element, className) {
  var classes = element.className.split(" ");
  for (var i in classes) {
    if (classes[i] == className) {
      return true;
    }
  }
  return false;
}

function addClass(element, className) {
  if (!hasClass(element, className)) {
    element.className = (element.className == "" ? className : element.className + " " + className);
  }
}
function removeClass(element, className) {
  var newValue = "";
  var classes = element.className.split(" ");
  for (var i in classes) {
    if (classes[i] != className) {
      newValue += newValue.length ? " " + classes[i] : classes[i];
    }
  }
  element.className = newValue;
}