Date-Mask_javascript スキルを使用して日付を文字列に変換する JavaScript メソッド

var MonthNames = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var DayNames = [ "Sunday", "Monday", "Tueday", "Wednesday", "Thursday", 
  "Friday", "Saturday" ];
var ShortMths = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", 
  "Sep", "Oct", "Nov", "Dec"];
var ShortDays = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
var StringToDate = function (sDate, sFormat, cutOff) {
  // Input: a date value as a string, it's format as a string e.g. 'dd-mmm-yy'
  // Optional: a cutoff (integer) for 2 digit years.
  // If no 'd' appears in the format string then the 1st of the month is assumed.
  // If the year is 20 and the cut-off is 30 then the value will be converted 
  // to 2020; if the year is 40 then this will be converted to 1940.
  // If no cut-off is supplied then '20' will be pre-pended to the year (YY).
  // Output: a string in the format 'YYYY/MM/DD' or ''
  // Will not attempt to convert certain combinations e.g. DMM, MDD, DDM, YYYYD.
  var sParsed, fndSingle;
  // sParsed will be constructed in the format 'YYYY/MM/DD'
  sDate = sDate.toString().toUpperCase();
  sFormat = sFormat.toUpperCase();
  if (sFormat.search(/MMMM|MMM/) + 1) { // replace Mar/March with 03, etc.
    sDate = sDate.replace(new RegExp('(' + ShortMths.join('|') + ')[A-Z]*', 'gi'),
      function (m) {
      var i = ShortMths.indexOf(m.charAt(0).toUpperCase() + 
        m.substr(1, 2).toLowerCase()) + 1;
      return ((i < 10) &#63; "0" + i : "" + i).toString();
    });
    sFormat = sFormat.replace(/MMMM|MMM/g, 'MM');
  }
  if (sFormat.search(/DDDD|DDD/) + 1) { // replace Tue/Tuesday, etc. with ''
    sDate = sDate.replace(new RegExp('(' + ShortDays.join('|') + ')[A-Z]*', 'gi'),'');
    sFormat = sFormat.replace(/DDDD|DDD/g, '');
  }
  sDate = sDate.replace(/(^|\D)(\d)(&#63;=\D|$)/g, function($0, $1, $2) {
    // single digits 2 with 02
    return $1 + '0' + $2;
  });
  sFormat = sFormat.replace(/(^|[^DMY])(D|M)(&#63;=[^DMY]|$)/g, function($0, $1, $2){
    return $1 + $2 + $2; // replace D or M with DD and MM
  });
  // are there still single Ds or Ms&#63;
  fndSingle = sFormat.search(/(^|[^D])D([^D]|$)|(^|[^M])M([^M]|$)/)+1;
  // do not attempt to parse, for example, 'DMM'
  if ( fndSingle ) return '';
  sFormat = sFormat.replace(/(^|[^Y])(YY)(&#63;=[^Y]|$)/g, function($0, $1, $2, index) {
    var tempDate = sDate.substr(0, index + 1);
    tempDate += (cutOff) &#63; ((parseInt(sDate.substr(index + 1, 2),10) > cutOff) &#63; '19' : '20') : '20';
    tempDate += sDate.substr(index + 1);
    sDate = tempDate;
    return $1 + $2 + $2;
  });
  sParsed = ('YYYY/MM/DD').replace(/YYYY|MM|DD/g, function(m){
    return (sFormat.indexOf(m) + 1) &#63; 
      sDate.substr(sFormat.indexOf(m), m.length) : '';
  });
  if (sParsed.charAt(0) == '/') {
    // if no year specified, assume the current year
    sParsed = (new Date().getFullYear()) + sParsed;
  }
  if (sParsed.charAt(sParsed.length - 1) == '/') {
    // if no date, assume the 1st of the month
    sParsed += '01';
  }
  // should end up with 10 characters..
  return ( sParsed.length == 10 ) &#63; sParsed : '';
};