How to debug Google Apps Script

In google docs spreadsheets, you can add some scripting functionality. If you are adding something for the onEdit event, but you don’t know if it’s working. As far as I can tell, you can’t debug a live event from google docs, so you have to do it from the debugger, which is pointless since the event argument passed to my onEdit() function will always be undefined if I run it from the Script Editor.

So, I was trying to use the Logger.log method to log some data whenever the onEdit function gets called, but this too seems like it only works when run from the Script Editor. When I run it from the Script Editor, I can view the logs by going to View->Logs...

I was hoping I’d be able to see the logs from when the event actually gets executed, but I can’t figure it out.

Logger.log will either send you an email (eventually) of errors that have happened in your scripts, or, if you are running things from the Script Editor, you can view the log from the last run function by going to View->Logs (still in script editor). Again, that will only show you anything that was logged from the last function you ran from inside Script Editor.

The script I was trying to get working had to do with spreadsheets – I made a spreadsheet todo-checklist type thing that sorted items by priorities and such.

The only triggers I installed for that script were the onOpen and onEdit triggers. Debugging the onEdit trigger was the hardest one to figure out, because I kept thinking that if I set a breakpoint in my onEdit function, opened the spreadsheet, edited a cell, that my breakpoint would be triggered. This is not the case.

To simulate having edited a cell, I did end up having to do something in the actual spreadsheet though. All I did was make sure the cell that I wanted it to treat as “edited” was selected, then in Script Editor, I would go to Run->onEdit. Then my breakpoint would be hit.

However, I did have to stop using the event argument that gets passed into the onEdit function – you can’t simulate that by doing Run->onEdit. Any info I needed from the spreadsheet, like which cell was selected, etc, I had to figure out manually.

Anyways, long answer, but I figured it out eventually.

function onOpen() {

function setCheckboxes() {
  var checklist = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("checklist");
  var checklist_data_range = checklist.getDataRange();
  var checklist_num_rows = checklist_data_range.getNumRows();
  Logger.log("checklist num rows: " + checklist_num_rows);

  var coredata = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("core_data");
  var coredata_data_range = coredata.getDataRange();

  for(var i = 0 ; i < checklist_num_rows-1; i++) {
    var split = checklist_data_range.getCell(i+2, 3).getValue().split(" || ");
    var item_id = split[split.length - 1];
    if(item_id != "") {
      item_id = parseInt(item_id);
      Logger.log("setting value at ("+(i+2)+",2) to " + coredata_data_range.getCell(item_id+1, 3).getValue());
      checklist_data_range.getCell(i+2,2).setValue(coredata_data_range.getCell(item_id+1, 3).getValue());

function onEdit() {
  var active_sheet = SpreadsheetApp.getActiveSheet();
  if(active_sheet.getName() == "checklist") {
    var active_range = SpreadsheetApp.getActiveSheet().getActiveRange();
    Logger.log("active_range: " + active_range);
    Logger.log("active range col: " + active_range.getColumn() + "active range row: " + active_range.getRow());
    Logger.log("active_range.value: " + active_range.getCell(1, 1).getValue());
    Logger.log("active_range. colidx: " + active_range.getColumnIndex());
    if(active_range.getCell(1,1).getValue() == "?" || active_range.getCell(1,1).getValue() == "?") {
      Logger.log("made it!");
      var next_cell = active_sheet.getRange(active_range.getRow(), active_range.getColumn()+1, 1, 1).getCell(1,1);
      var val = next_cell.getValue();
      Logger.log("val: " + val);
      var splits = val.split(" || ");
      var item_id = splits[splits.length-1];
      Logger.log("item_id: " + item_id);

      var core_data = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("core_data");
      var sheet_data_range = core_data.getDataRange();
      var num_rows = sheet_data_range.getNumRows();
      var sheet_values = sheet_data_range.getValues();
      Logger.log("num_rows: " + num_rows);

      for(var i = 0; i < num_rows; i++) {
        Logger.log("sheet_values[" + (i) + "][" + (8) + "] = " + sheet_values[i][8]);
        if(sheet_values[i][8] == item_id) {
          Logger.log("found it! tyring to set it...");
          sheet_data_range.getCell(i+1, 2+1).setValue(active_range.getCell(1,1).getValue());



If you’re coding in a spreadsheet-contained script, for example, you can add just this one line to the top of your script file, and all logs will go to a “Logs” sheet in the spreadsheet. No other code necessary, just use Logger.log() as you usually would:

Logger = BetterLog.useSpreadsheet();


Written By:

Sarmad Gardezi A blog scientist by Mind and a Passionate Blogger by heart. Sarmad is Freelancer, Entrepreneur and Google Apps Scripts Developer from Islamabad, Pakistan.

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