docs: function removeElClass(element, classToRemove) {
    if (element.classList) {
      element.classList.remove(classToRemove);
    } else {
      throwIfWhitespace(classToRemove);
      element.className = element.className.split(/\s+/).filter(function (c) {
        return c !== classToRemove;
      }).join(' ');
    }
  
    return element;
  }