How to debug Google Apps Script (aka where does Logger.log log to?)

user_606473 0
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In Google Sheets, you can add some scripting functionality. I'm adding something for the onEdit event, but I can't tell if it's working. As far as I can tell, you can't debug a live event from Google Sheets, 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.

How do I debug this stuff?

google-apps-script google-sheets triggers debugging
12 Answers

2017 Update: Stackdriver Logging is now available for Google Apps Script. From the menu bar in the script editor, goto: View > Stackdriver Logging to view or stream the logs.

console.log() will write DEBUG level messages

Example onEdit() logging:

function onEdit (e) {
  var debug_e = {
    authMode:  e.authMode,  
    range:  e.range.getA1Notation(),    
    source:  e.source.getId(),
    user:  e.user,   
    value:  e.value,
    oldValue: e. oldValue
  }

  console.log({message: 'onEdit() Event Object', eventObject: debug_e});
}

Then check the logs in the Stackdriver UI labeled onEdit() Event Object to see the output

user_82729520

I've gone through these posts and somehow ended up finding a simple answer, which I'm posting here for those how want short and sweet solutions:

  1. Use console.log("Hello World") in your script.
  2. Go to https://script.google.com/home/my and select your add-on.
  3. Click on the ellipsis menu on Project Details, select Executions.

enter image description here

  1. Click on the header of the latest execution and read the log.

enter image description here

user_7174410

If you have the script editor open you will see the logs under View->Logs. If your script has an onedit trigger, make a change to the spreadsheet which should trigger the function with the script editor opened in a second tab. Then go to the script editor tab and open the log. You will see whatever your function passes to the logger.

Basically as long as the script editor is open, the event will write to the log and show it for you. It will not show if someone else is in the file elsewhere.

user_33542260

The dev console will log errors thrown by the app script, so you can just throw an error to get it logged as a normal console.log. It will stop execution, but it might still be useful for step by step debugging.

throw Error('hello world!');

will show up in the console similarly to console.log('hello world')

user_2907900

just debug your spreadsheet code like this:

...
throw whatAmI;
...

shows like this:

enter image description here

user_5334260
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