Class Logger
Page Summary
The Logger class is used to write to the Execution log and Google Cloud Logging, especially for structured logging and JSON payloads.
Use the clear() method to clear the log and getLog() to retrieve all messages in the current log.
The log() method can write various data types to the log, including strings, JavaScript objects, or objects with a message property.
The log() method also supports writing formatted strings to the log using placeholders and values.
This class allows the developer to write to the Execution log and toGoogle Cloud Logging if the script is associated withastandardCloud Project. This class is preferred for structured logging andjson supportin Cloud Logging. For time-based logging, useconsole.
Methods
| Method | Return type | Brief description |
|---|---|---|
clear() | void | Clears the log. |
get | String | Returns a complete list of messages in the current log. |
log(data) | Logger | Writes the data to the log. |
log(format, values) | Logger | Writes a formatted string to the logging console, using the format and values provided. |
Detailed documentation
clear()
Clears the log.
getLog()
Returns a complete list of messages in the current log. This method can be used to save oremail the entire log output generated during script execution.
// Generate a log, then email it to the person who ran the script.constfiles=DriveApp.getFiles();while(files.hasNext()){Logger.log(files.next().getName());}constrecipient=Session.getActiveUser().getEmail();constsubject='A list of files in your Google Drive';constbody=Logger.getLog();MailApp.sendEmail(recipient,subject,body);
Return
String — the log from the logging console
log(data)
Writes the data to the log. The data can be a string, a JavaScript object, or an object with amessage property.
Logger.log("my log message");// Info my logmessageLogger.log({key:"value"});// Info {key=value}Logger.log({message:"my log message",data:{key:"value"}})// Info my logmessage
When passing an object, if the object contains amessage property, that property isused as the log message. Otherwise, theto method is called to convert theobject to a string. All other properties which are JSON serializable are included as part ofthejson in theLog, similar to the example below:
{"insertId":"w5eib...","jsonPayload":{"message":"my log message","serviceContext":{"service":"AKfyc..."},"data":{"key":"value"}},"resource":{"type":"app_script_function","labels":{"invocation_type":"editor","function_name":"unknown","project_id":"1234567890"}},"timestamp":"2024-11-15T23:28:19.448591Z","severity":"INFO","labels":{"script.googleapis.com/user_key":"AOX2d...","script.googleapis.com/process_id":"EAEA1...","script.googleapis.com/project_key":"MQXvl...","script.googleapis.com/deployment_id":"AKfyc..."},"logName":"projects/[PROJECT_ID]/logs/script.googleapis.com%2Fconsole_logs","receiveTimestamp":"2024-11-15T23:28:20.363790313Z"}
Parameters
| Name | Type | Description |
|---|---|---|
data | Object | the object to log |
Return
Logger — the Logger, for chaining.
log(format, values)
Writes a formatted string to the logging console, using the format and values provided. Thestring can include multiple%s placeholders, which are replaced with correspondingvalues from the list of arguments, converted to strings.
// Log the number of Google Groups you belong to.constgroups=GroupsApp.getGroups();Logger.log('You are a member of %s Google Groups.',groups.length);
Parameters
| Name | Type | Description |
|---|---|---|
format | String | a format string that contains as many instances of%s as the number ofvalues arguments |
values | Object... | a variable number of values to insert into the format string |
Return
Logger — the Logger, for chaining
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Last updated 2025-12-11 UTC.