function setClass(id, classname) {
  document.getElementById(id).className=classname;
}

function hasClass(ele,cls) {
  return ele.className.match(new RegExp('(\\s|^)'+cls+'(\\s|$)'));
}

function addClass(ele,cls) {
  if (!this.hasClass(ele,cls)) ele.className += " "+cls;
}

function removeClass(ele,cls) {
  if (hasClass(ele,cls)) {
    var reg = new RegExp('(\\s|^)'+cls+'(\\s|$)');
    ele.className=ele.className.replace(reg,' ');
  }
}