function getFirestore() {
  var email = "xxx";
  var key = "xxx";
  var projectId = "xxx";
  return FirestoreApp.getFirestore(email,key,projectId);
}

function myFunction() {
  // 1. Initialize Variables
  const firestore=getFirestore();

  // 2. Get The Data from spreadsheet
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheetname = "tinggal";
  var sheet = ss.getSheetByName(sheetname);
  var lastRow = sheet.getLastRow();
  var lastCol = sheet.getLastColumn();
  var dataSR = 2; //baris 1 untuk nama kolom

  // define the data range
  var sheetRange = sheet.getRange(2,1,lastRow-dataSR+1,lastCol);

  // get the data
  var sheetData = sheetRange.getValues();

  // get the number of length of the object in order to establish a loop value
  var sourceLen = sheetData.length;

  // 3. Loop for insert the data
  for (var i=0; i<sourceLen; i++){

    if (sheetData[i][1] !== ''){
      var data = {};
      data.nama = sheetData[i][0];
      data.negara = sheetData[i][1];
      data.umur = sheetData[i][2];
      data.kota = sheetData[i][3];
      Logger.log(data);
      firestore.createDocument("surat", data);
    }

  }

}