docs: function hasClass(element, className) {
      !!/\s/.test(className) ? "development" !== 'production' ? invariant(false, 'CSS.hasClass takes only a single class name.') : invariant(false) : void 0;
      if (element.classList) {
        return !!className && element.classList.contains(className);
      }
      return (' ' + element.className + ' ').indexOf(' ' + className + ' ') > -1;
    }