code: function removeClass(element, className) {
    var classNames = className;
  
    function _removeClass(el, cn) {
      var classRegex;
      if (el.classList) {
        el.classList.remove(cn);
      } else {
        classRegex = new RegExp('(?:^|\\s)' + cn + '(?!\\S)', 'g');
        el.className = el.className.replace(classRegex, '').trim();
      }
    }
  
    if (!isArray(className)) {
      classNames = className.trim().split(/\s+/);
    }
    classNames.forEach(_removeClass.bind(null, element));
  
    return element;
  }
docs: Remove a class from an element
  @param  {Element} element
  @param  {Array.<string>|String} array of classnames or string with
  @return {Element}