https://www.katoart.jp/js/setting_sidebar.js

1function loadsidebarArchive() {
2  let releaseDatesData = $("#release-date-list").attr("data-release-dates")
3  if (releaseDatesData == undefined) return;
4
5  let releaseDates = JSON.parse(releaseDatesData);
6  if (releaseDates.length == 0) return;
7
8  let elementReleaseDates = []
9  let yearLocal = []
10  for (let date of releaseDates) {
11    let dateString = date.replaceAll('-', '/');
12    let dateLocal = new Date(dateString).toLocaleString('ja-JP', { year: 'numeric', month: 'numeric', day: 'numeric' });
13    elementReleaseDates.push(dateLocal.split("/"))
14    let year = dateLocal.split("/")[0]
15    if (!yearLocal.includes(year)) yearLocal.push(year) 
16  }
17
18  let listArchive = []
19  for (let year of yearLocal) {
20    let monthLocalOfYear = []
21    for (let date of elementReleaseDates) {
22      if (date[0] == year) {
23        monthLocalOfYear.push(date[1])
24      }
25    }
26    let monthUnique = [...new Set(monthLocalOfYear)];
27    let listMonth = []
28    for (let month of monthUnique) {
29      let countMonth = monthLocalOfYear.filter(i => i == month).length
30      listMonth.push({month: month, count: countMonth})
31    }
32    listArchive.push({year: year, listMonth: listMonth})
33  }
34
35  let sidebarArchive = ""
36  for (let archive of listArchive) {
37    sidebarArchive += `<li><a href="javascript:void(0)">${archive['year']}å¹´</a><ul style="display: none;">`
38    for (let month of archive['listMonth']) {
39      sidebarArchive += `<li><a href="javascript:void(0)" 
40        class="archive-month-item" data-release-year="${archive['year']}" data-release-month="${month['month']}">
41        ${month['month']}月 (${month['count']})</a></li>`
42    }
43    sidebarArchive += `</ul>`
44  }
45  $("#sidebar-list-archive").html(sidebarArchive);
46}