If you had read the next sentence of my comments you would have seen that it would be a "few more lines" if you didn't use jQuery, basically you need a function like:

  function eachItem(arrayLike, cb) {
    return [].slice.call(arrayLike).forEach(cb);
  }

So 3 more lines. If I said you can write a very verbose accordion in under 20 lines would that be good enough for you?

I'm not sure why the actual jQuery library matters here. Chances are if you're using jQuery for an accordion you're also using it for a lot of other things.