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,' ');
  }
}
 
//call the functions
addClass(document.getElementById("test"), "test");
removeClass(document.getElementById("test"), "test")
if(hasClass(document.getElementById("test"), "test")){//do something};