text: function addClass(el, classNames) {
    var className;
    if (!classNames) return;
    if (classNames.constructor !== Array) {
      classNames = [classNames];
    }
    if (el.classList) {
      classNames.forEach(function(className) {
        el.classList.add(className);
      });
    } else {
      el.className += " " + className.join(" ");
    }
  }
  
  export default addClass;
  