Class Logger  |  Apps Script  |  Google for Developers (original) (raw)

Class Logger

• 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.

Logger

This class allows the developer to write to the Execution log and to Google Cloud Logging if the script is associated with a standard Cloud Project. This class is preferred for structured logging and jsonPayload support in Cloud Logging. For time-based logging, use [console](/apps-script/reference/base/console).

Methods

Detailed documentation

getLog()

Returns a complete list of messages in the current log. This method can be used to save or email the entire log output generated during script execution.

// Generate a log, then email it to the person who ran the script. const files = DriveApp.getFiles(); while (files.hasNext()) { Logger.log(files.next().getName()); } const recipient = Session.getActiveUser().getEmail(); const subject = 'A list of files in your Google Drive'; const body = 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 logmessage Logger.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 a message property, that property is used as the log message. Otherwise, the toString() method is called to convert the object to a string. All other properties which are JSON serializable are included as part of the jsonPayload in the LogEntry, 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

Return

[Logger](#) — the Logger, for chaining.

log(format, values)

Writes a formatted string to the logging console, using the format and values provided. The string can include multiple %s placeholders, which are replaced with corresponding values from the list of arguments, converted to strings.

// Log the number of Google Groups you belong to. const groups = GroupsApp.getGroups(); Logger.log('You are a member of %s Google Groups.', groups.length);

Parameters

Return

[Logger](#) — the Logger, for chaining

Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025-12-11 UTC.