https://mp1.petfamilyins.co.jp/exex-pafWeb-MyPage/resources/lib/script/format_utils.js

1/* 日時フォーマット */
2function dateFormat(s)
3{
4	  var str = (s.val());
5	  if(str.match(/[0-9]{8}/))
6	  {
7		  t = str.substring(0,4)+"/"+str.substring(4,6)+"/"+str.substring(6,8);
8		  s.val(t);
9	  }
10	  if(str.match(/^\d{2,4}\/\d{1,2}\/\d{1,2}$/))
11	  {
12		  var strList = new Array();
13		  strList = str.split("/");
14		  var yyyy = strList[0];
15		  var mm = strList[1];
16		  var dd = strList[2];
17		  //月が1桁の場合
18		  if(mm.length == 1){
19			  mm = "0" + mm;
20		  }
21		  //日が1桁の場合
22		  if(dd.length == 1){
23			  dd = "0" + dd;
24		  }
25		  t = yyyy+"/"+mm+"/"+dd;
26		  s.val(t);
27	  }
28};