Printing to the console in Google Apps Script

Question

I am very new to programming  have taken some of the JS courses on Codecademy   I am trying to create a simple script to determine  if given a spreadsheet with results from a poker game  who should pay whom  I opened up Google Apps Script  and wrote the following to get started   function addplayerstoArray numplayers       var playerArray          for  i 0  i lt numplayers  i          playerArray push i            addplayerstoArray 7    console log playerArray 3     The idea is to create an array with the total number of players in it  When running the code  I thought it would print  3  to the console  But nothing happened  It said       ReferenceError   console  is not defined      A  What do I not understand about how the Google Apps Script console works with respect to printing so that I can see if my code is accomplishing what I d like   B  Is it a problem with the code

User · Answer

In a google script project you can create html files (example: index.html) or gs files (example:code.gs). The .gs files are executed on the server and you can use Logger.log as @Peter Herrman describes. However if the function is created in a .html file it is being executed on the user's browser and you can use console.log. The Chrome browser console can be viewed by Ctrl Shift J on Windows/Linux or Cmd Opt J on Mac

If you want to use Logger.log on an html file you can use a scriptlet to call the Logger.log function from the html file. To do so you would insert <? Logger.log(something) ?> replacing something with whatever you want to log. Standard scriptlets, which use the syntax <? ... ?>, execute code without explicitly outputting content to the page.

User · Answer

Just to build on vinnief s hacky solution above  I use MsgBox like this   Browser msgBox  BorderoToMatriz   Browser Buttons OK CANCEL     and it acts kinda like a break point  stops the script and outputs whatever string you need to a pop-up box   I find especially in Sheets  where I have trouble with Logger log  this provides an adequate workaround most times

User · Answer

Updated for 2020 In February of 2020  Google announced a major upgrade to the built-in Google Apps Script IDE  and it now supports console log    So  you can now use both   Logger log   console log    Happy coding

User · Answer

The console is not available because the code is running in the cloud  not in your browser  Instead  use the Logger class provided by GAS   Logger log playerArray 3     and then view the results in the IDE under View   Logs     Here s some documentation on logging with GAS   Edit  2017-07-20  Apps script now also provides Stackdriver Logging  View these logs in the script editor under View - Console Logs

User · Answer

Make sure you select the function that needs to be executed  See screenshot

User · Answer

Even though Logger log   is technically the correct way to output something to the console  it has a few annoyances    The output can be an unstructured mess and hard to quickly digest  You have to first run the script  then click View   Logs  which is two extra clicks  one if you remember the Ctrl Enter keyboard shortcut   You have to insert Logger log playerArray   and then after debugging you d probably want to remove Logger log playerArray   hence an additional 1-2 more steps  You have to click on OK to close the overlay  yet another extra click     Instead  whenever I want to debug something I add breakpoints  click on line number  and press the Debug button  bug icon   Breakpoints work well when you are assigning something to a variable  but not so well when you are initiating a variable and want to peek inside of it at a later point  which is similar to what the op is trying to do  In this case  I would force a break condition by entering  x   x marks the spot   to throw a run-time error     Compare with viewing Logs     The Debug console contains more information and is a lot easier to read than the Logs overlay  One minor benefit with this method is that you never have to worry about polluting your code with a bunch of logging commands if keeping clean code is your thing  Even if you enter  x   you are forced to remember to remove it as part of the debugging process or else your code won t run  built-in cleanup measure  yay

User · Answer

Answering the OP questions     A  What do I not understand about how the Google Apps Script console works with respect to printing so that I can see if my code is accomplishing what I d like    The code on  gs files of a Google Apps Script project run on the server rather than on the web browser  The way to log messages was to use the Class Logger       B  Is it a problem with the code    As the error message said  the problem was that console was not defined but nowadays the same code will throw other error      ReferenceError   playerArray  is not defined   line 12  file  Code      That is because the playerArray is defined as local variable  Moving the line out of the function will solve this   var playerArray        function addplayerstoArray numplayers      for  i 0  i lt numplayers  i          playerArray push i            addplayerstoArray 7    console log playerArray 3     Now that the code executes without throwing errors  instead to look at the browser console we should look at the Stackdriver Logging  From the Google Apps Script editor UI click on View   Stackdriver Logging   Addendum  On 2017 Google released to all scripts Stackdriver Logging and added the Class Console  so including something like console log  Hello world    will not throw an error but the log will be on Google Cloud Platform Stackdriver Logging Service instead of the browser console   From Google Apps Script Release Notes 2017     June 23  2017        Stackdriver Logging has been moved out of Early Access  All scripts now have access to Stackdriver logging    From Logging   Stackdriver logging     The following example shows how to use the console service to log information in Stackdriver   function measuringExecutionTime          A simple INFO log message  using sprintf   formatting    console info  Timing the  s function   d arguments     myFunction   1         Log a JSON object at a DEBUG level  The log is labeled      with the message string in the log viewer  and the JSON content      is displayed in the expanded log structure under  structPayload     var parameters           isValid  true        content   some string         timestamp  new Date          console log  message   Function Input   initialData  parameters       var label    myFunction   time       Labels the timing log entry    console time label                   Starts the timer    try       myFunction parameters              Function to time      catch  e           Logs an ERROR message      console error  myFunction   yielded an error      e         console timeEnd label           Stops the timer  logs execution duration

[logging] Printing to the console in Google Apps Script?

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