AR Script: add time offset to datetimeoriginal

  const OFFSET_SEC  = 0;
  const OFFSET_MIN  = 0;
  const OFFSET_HR   = 0;

  const POS_YR = 1, POS_MNT = 2, POS_DAY = 3, POS_HR = 4, POS_MIN = 5, POS_SEC = 6;

  var hrs = 0, min = 0, sec = 0;

    var DTO = "";
    var aDateTime = [];
    //regular expression to extract date from datetimeoriginal (which is a date and a time)
    var reDateTimeSplit = /(\d{4}):(\d{2}):(\d{2})\s(\d{2}):(\d{2}):(\d{2})/;
    //extract datetimeoriginal from file
    DTO = app.getItem(index).exifToolValue("DateTimeOriginal");

    if (DTO.length != 0) {
    aDateTime = reDateTimeSplit.exec(DTO);

    // add the datetimeoriginal values with the offsets
    hrs = Number(aDateTime[POS_HR]) + OFFSET_HR;
    min = Number(aDateTime[POS_MIN]) + OFFSET_MIN;
    sec = Number(aDateTime[POS_SEC]) + OFFSET_SEC;

    // convert seconds to minutes and minutes to hours if the offset goes beyond 60 sec or 60 min
    min+= (sec - (sec % 60)) / 60;
    hrs+= (min - (min % 60)) / 60;
    min%= 60;
    sec%= 60;

    //return the final value
        return aDateTime[POS_YR] + aDateTime[POS_MNT] + aDateTime[POS_DAY] + "_" + zpad(hrs.toString(), 2) + zpad(min.toString(), 2) + zpad(sec.toString(), 2);
        }
    else{
        return null
    }

// Function that add leading zeros to any string
function zpad(str, nb_digits) {
    if (str.length < nb_digits)     { return (Array(nb_digits - str.length + 1).join('0') + str); }
    else                            { return str; }
}