There is nothing in this kata that should make it worth kyu 5.

However it's not useful to complain

I disagree. It is useful to complain because a) it's a signal that something is wrong which is affecting the user experience, b) the comments will be useful when organizing future cleanup efforts, should it eventually become easier to rerank and c) they provide opportunity for discussion about matters that affect site quality.

If someone takes the time to leave a comment about a ranking, then it probably reeled their expectations enough to be worth a look; not only is this useful for people who are less sensitive to challenge gradations at the lower ranks, but it can also be reassuring to less experienced warriors who would otherwise be put off.

do you have a right example how to solve it with closures?

I'm sorry .reset() got you confused. You choose to focus on the wrong things. The template is quite straightforward:

DocumentParser.prototype.parse = function()
{
  // TODO: Code Here!
};

it means if next exists, then add '- ${next}'
lets say for exapmple when byDay.prev and byDay.cur are not equal
next is just '' empty stroke, so we dont add - ${next}

seems like this merits a spoiler

Nice usage of IIFE and comma operator.

Elegant readable solution showing how useful recursion can be.

Nice solution, very readable.