I can’t really think of something that provides a direct mentor, but both code wars and leetcode are goodd places to practice challenges. You could of course ask people on the forum what they think of your code as well.
Well, you can check every alternative which they don’t have mentors, but only problems, like HackerRank, Codewars, SPOJ, TopCoder, Codechef, Project Euler, atCoder (if you want). If you want even mentors in the mix I suggest two things: or go premium (I heard there are more faster mentors) or go to CodingCoach and hope to find a fast coach, maybe ask him to teach you about this and you are done.
This is daft, you’re expecting far too much. These are volunteers. They aren’t at your beck and call. They are normally quick, particularly for a very popular language like JS. And a week is quick: there are thousands of learners and few mentors.
You can pay someone to mentor you, there will not be shortage of people who will do that and the feedback will be much quicker.That’s the alternative.