2つの日付,営業日数の計算

main();
function main(){
//////// START "main()" /////////////////////////////////////////////////////////////////
//// == Config Retrieving / 工程コンフィグの参照 ==
const numDataIdA = configs.get("conf_DataIdA");
const numDataIdB = configs.get("conf_DataIdB");
const holidayMasterFileName = configs.get("conf_HolidayMasterFileName");
const strIsShare        = configs.get("conf_IsShareHolidayMaster");
const closedDaysConfigs = configs.get("conf_DataIdE");
const numDataIdF        = configs.get("conf_DataIdF");

//// == Data Retrieving / ワークフローデータの参照 ==
let startDate = engine.findDataByNumber( numDataIdA );
let endDate   = engine.findDataByNumber( numDataIdB );
let strEndDate = "";
//// == Calculating / 演算 ==
if ( startDate === null){
  engine.log("Start Date is null. Business Day Count is zero.");
  engine.setDataByNumber( numDataIdF, new java.math.BigDecimal( 0 ) );
  return;
}
if ( endDate === null ){
  engine.log("End Date is null. Force Set Today to End Date.");
  let now = new Date();
  endDate = java.sql.Date.valueOf(now.getFullYear() + "-" + (now.getMonth()+1).toString().padStart(2, '0') + "-" + now.getDate().toString().padStart(2, '0'));
  engine.setDataByNumber( numDataIdB , endDate);
  now.setDate(now.getDate() + 1 );
  strEndDate = now.getFullYear() + "-" + (now.getMonth()+1).toString().padStart(2, '0') + "-" + now.getDate().toString().padStart(2, '0');
}else{
  strEndDate = endDate.addDays(1) + "";
}
engine.log("strEndDate: " + strEndDate);
const milliSecStartDate = toJsDate( startDate + "").getTime();
const milliSecEndDate = toJsDate( strEndDate ).getTime();  // include last day
const milliSecDuration = milliSecEndDate - milliSecStartDate;

if ( milliSecStartDate >= milliSecEndDate ){
  engine.log("Start Date >= End Date. Business Day Count is zero.");
  engine.setDataByNumber( numDataIdF, new java.math.BigDecimal( 0 ) );
  return;
}

let excludeCount = 0;
let closedDays = new Array();
if (closedDaysConfigs !== null){
    closedDays = closedDaysConfigs.split("\n");
}
engine.log("closedDays lenght: " + closedDays.length);
const allDurationDaysCount =  milliSecDuration /1000 /60 /60 /24 ;
engine.log("All Duration Days: " + allDurationDaysCount);

let isShare = true;
if (strIsShare === "false"){
  isShare = false;
}
// Holiday Master Check
const holidayConfigList = itemDao.findAll( holidayMasterFileName , isShare);
for (let i=0; i < holidayConfigList.size(); i++){
  let config = holidayConfigList.get(i);
  let dateObjHoriday = toJsDate( config.getValue() );
  let milliSecHoridayDate = toJsDate( config.getValue() ).getTime();
  let horidayName = config.getDisplay();
  if (( milliSecStartDate <= milliSecHoridayDate )&&( milliSecEndDate >= milliSecHoridayDate )){
    engine.log("Exclude Holiday: " + config.getValue() + " " + horidayName);
    excludeCount++;
    // Avoid Duplication (Holiday and Weekly Closed Day)
    for (let j=0; j < closedDays.length; j++){
      let closedDay = closedDays[j].split(",");
      if (closedDay[0] === (dateObjHoriday.getDay() + "")){
        engine.log(config.getValue() + " " + horidayName + " " + closedDay[1]);
        excludeCount--;
        break;
      }
    }
  }
}
// "Days of Week to be Closed" Check
for (let i=0; i < allDurationDaysCount; i++){
  let dateObjTargetDate =  toJsDate( startDate.addDays(i) + "" );
  for (let j=0; j < closedDays.length; j++){
    let closedDay = closedDays[j].split(",");
    if (closedDay[0] === (dateObjTargetDate.getDay() + "")){
      engine.log("Exclude Close Days: " + (startDate.addDays(i) + ""));
      excludeCount++;
      break;
    }
  }
}
//// == Data Updating / ワークフローデータへの代入 ==
engine.log("Exclude Count: " + excludeCount);
engine.log("Business Days Count: " + (allDurationDaysCount - excludeCount));
engine.setDataByNumber( numDataIdF , new java.math.BigDecimal(allDurationDaysCount - excludeCount) );
} //////// END "main()" /////////////////////////////////////////////////////////////////

function toJsDate( bpmsDateOrDatetimeStr ){
// BPMS Date:     "2020-04-01"  (subtype "Y/M" "M/D" "Y", not supported)
// BPMS Datetime: "2020-04-01 23:59"
let year       = 0;
let monthIndex = 0;
let day        = 0;
let hours      = 0;
let minutes    = 0;

//  The ECMA/JavaScript Date object has a large number of methods.
// "Date.parse" is danger (strongly discouraged)
// - new Date("2014-11-10") // Mon Nov 10 2014 09:00:00 GMT+0900 (JST)
// - new Date(2014, 10, 10) // Mon Nov 10 2014 00:00:00 GMT+0900 (JST)
let arrDatetime = bpmsDateOrDatetimeStr.split(" ");
if( arrDatetime.length === 1 ){
  let arrDateParts = arrDatetime[0].split("-");
  year       = parseInt(arrDateParts[0], 10);
  monthIndex = parseInt(arrDateParts[1], 10) - 1;
  day        = parseInt(arrDateParts[2], 10);
}
if( arrDatetime.length === 2 ){
  let arrDateParts = arrDatetime[0].split("-");
  let arrTimeParts = arrDatetime[1].split(":");
  year       = parseInt(arrDateParts[0], 10);
  monthIndex = parseInt(arrDateParts[1], 10) - 1;
  day        = parseInt(arrDateParts[2], 10);
  hours      = parseInt(arrTimeParts[0], 10);
  minutes    = parseInt(arrTimeParts[1], 10);
}
return new Date( year, monthIndex, day, hours, minutes );
}