https://jingukaikan.jp/kaikan/js/timer.js

1$(document).ready(function() {
2  $(".view_timer").each(function(index, target) {
3    var startDate = $(this).attr("data-start-date");
4    var endDate = $(this).attr("data-end-date");
5    var nowDate = new Date();
6
7    if (startDate) {
8      startDate = new Date(startDate);
9    } else {
10      startDate = nowDate;
11    }
12    if (endDate) {
13      endDate = new Date(endDate);
14    }
15
16    if (startDate <= nowDate && (!endDate || nowDate <= endDate)) {
17      $(this).show();
18    } else {
19      $(this).hide();
20    }
21  });
22});