set_data_custom(formData)

1. 由於處理順序是由後面往前，故可設formData={}，然後在函式內先設定值，把寫入完成
2. 程式碼

/*========================================
  設定客戶資料 
=========================================*/
function set_data_custom(formData={}) {

  let sheet = 'day2';
  let ws = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheet);
  let stru = get_stru_custom();
  let rowIndex;

  // ---------------------------------寫入一筆記錄
  rowIndex = ws.getLastRow() + 1;
  // 暫時資料
  formData = { sn: rowIndex-1, title: 'test', tel: '0123456789', addr: 'aaaa', ps: 'bbbb' };
  
  for (let i in stru) {
    let colIndex = Number(i) + 1;//i 型態為字串，須轉為數字做計算
    setCellData(sheet, rowIndex, colIndex, formData[stru[i]['form_name']], stru[i]['type']);
  }
  // ---------------------------------寫入一筆記錄 end

}

3. 新增 or 編輯
   判斷formData['sn']是否有傳值，有值則是編輯，空值則是新增
   新增的列指標 rowIndex = ws.getLastRow() + 1
   編輯的列指標
   1. 取得流水號欄的資料 snData = [1, 2, .......]
   2. 然後搜尋 snIndex = snData.indexOf(Number(formData.sn))
   3. snIndex == -1 無此資料，回報錯畫面
   4. rowIndex = snIndex + 2
   5. 函式 get_rowIndex(sheet, sn)

/*========================================
  取得列指標
  找不到 回傳 -1
=========================================*/
function get_rowIndex(sheet, sn){
  if(!sheet || !sn)return -1;
  let ss = SpreadsheetApp.getActiveSpreadsheet()
  let ws = ss.getSheetByName(sheet);
  if (ws=== null || ws.getLastRow() < 2) return -1;//尚無資料，返回-1
  let colArray = ws.getRange(2, 1, ws.getLastRow() - 1).getValues().map(function(row){
    return row[0];
  });
  let rowIndex = colArray.indexOf(Number(sn));
  if(rowIndex !== -1){
    rowIndex += 2;
  }
  return rowIndex;
}

4. set_data_custom(formData={})

/*========================================
  設定客戶資料 
=========================================*/
function set_data_custom(formData={}) {

  let sheet = 'day2';
  let ws = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheet);
  let stru = get_stru_custom();
  let rowIndex;

  // 暫時資料
  formData = { sn: '4', title: 'test', tel: '0123456789', addr: 'aaaa', ps: 'bbbb' };
  
  // 取得列指標
  if(formData.sn){//編輯
    rowIndex = get_rowIndex(sheet, formData.sn);
    if(rowIndex === -1){
      //報錯畫面
    }
  }else{//新增
    rowIndex = ws.getLastRow() + 1;
    // 指定流水號
    formData.sn = maxSn(sheet);
  }
  
  // 寫入工作表
  for (let i in stru) {
    let colIndex = Number(i) + 1;//i 型態為字串，須轉為數字做計算
    setCellData(sheet, rowIndex, colIndex, formData[stru[i]['form_name']], stru[i]['type']);
  }
  // ---------------------------------寫入一筆記錄 end

}