Google apps script to export an individual sheet as csv file

export-named-sheet-as-csv.gs

/*
 * script to export data of the named sheet as an individual csv files
 * sheet downloaded to Google Drive and then downloaded as a CSV file
 * file named according to the name of the sheet
 * original author: Michael Derazon (https://gist.github.com/mderazon/9655893)
*/

var delimiter = ';';

function onOpen() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var csvMenuEntries = [{name: "Download As CSV", functionName: "saveAsCSV"}];
  ss.addMenu("Create Custom CSV", csvMenuEntries);
};

function saveAsCSV() {
  var ss = SpreadsheetApp.getActiveSpreadsheet(); 
  var sheet = ss.getSheetByName('COPY');
  var dlName = ss.getSheetByName('Perms').getRange('A2').getValue();
  // create a folder from the name of the spreadsheet
  var folder = DriveApp.createFolder(ss.getName().toLowerCase().replace(/ /g,'_') + '_csv_' + new Date().getTime());
  // append ".csv" extension to the sheet name
  fileName = dlName + " Permissions.csv";
//  fileName = sheet.getName() + ".csv";
  // convert all available sheet data to csv format
  var csvFile = convertRangeToCsvFile_(fileName, sheet);
  // create a file in the Docs List with the given name and the csv data
  var file = folder.createFile(fileName, csvFile);
  //File downlaod
  var downloadURL = file.getDownloadUrl().slice(0, -8);
  showurl(downloadURL);
  
}

function showurl(downloadURL) {
   var link = HtmlService.createHtmlOutput('<a href="' + downloadURL + '">Click here to download</a>');
  SpreadsheetApp.getUi().showModalDialog(link, 'Your CSV file is ready!');
}

function convertRangeToCsvFile_(csvFileName, sheet) {
  // get available data range in the spreadsheet
  var activeRange = sheet.getDataRange();
  try {
    var data = activeRange.getValues();
    var csvFile = undefined;

    // loop through the data in the range and build a string with the csv data
    if (data.length > 1) {
      var csv = "";
      for (var row = 0; row < data.length; row++) {
        for (var col = 0; col < data[row].length; col++) {
          if (data[row][col].toString().indexOf(",") != -1) {
            data[row][col] = "\"" + data[row][col] + "\"";
          }
        }

        // join each row's columns
        // add a carriage return to end of each row, except for the last one
        if (row < data.length-1) {
          csv += data[row].join(delimiter) + "\r\n";
        }
        else {
          csv += data[row];
        }
      }
      csvFile = csv;
    }
    return csvFile;
  }
  catch(err) {
    Logger.log(err);
    Browser.msgBox(err);
  }
}

Is there a version of this that will maintain date and time formatting in the sheet tab being downloaded as CSV? This code works great but it coverts all of my date and times to the wrong format.