What is a Trigger and How to Utilize It?


In Google Apps Script, we use triggers as functions that can automatically run a script based on specific events and schedules. Triggers play an important role in automating workflow and reducing the manual tasks in Google Workspace applications. Triggers help in running scripts at designated times whenever the document is accessed or submitted and spreadsheet cells are edited.


How to Use a Trigger?


  1. Open Google Apps Script by navigating to Extensions > Apps Script in Google Sheets, Docs, or Forms.

  2. Write the function you want to trigger.

  3. Click on the Triggers (clock icon) in the left panel.

  4. Click + Add Trigger and select the function you created.

  5. Choose the event type (time-driven, onEdit, onFormSubmit, etc.).

  6. Configure additional options and click Save.

Add trigger fir trigger

There are two main types of triggers:


  1. Simple Triggers – Quick and easy but with limitations.

  2. Installable Triggers – More powerful, requiring user authorization.

Simple triggers are automatically built-in but installable triggers need user authorization to use but it provide more functionality to the user.


If you have the knowledge of these triggers you can automate repetitive tasks, and save your time and efforts.


Simple vs. Installable Triggers


Simple Triggers


To run simple trigger you do not need any kind of additional setup as it runs automatically. These are 3 most used  simple trigger:


  • onOpen() – Runs when a user opens a Google Sheet, Doc, or Form.

  • onEdit() – Executes when a user edits a Google Sheet.

  • onInstall() – Runs when an add-on is installed.

Example of a Simple Trigger:


function onOpen() {
  SpreadsheetApp.getUi().alert("Welcome! This sheet is now open.");
}

Limitations of Simple Triggers:


  • Cannot access external services (e.g., Gmail, Drive)

  • Cannot run longer than 30 seconds

  • Cannot use user authentication

Installable Triggers


Installable triggers provide more control and functionality, allowing you to:


  • Send emails

  • Access external services

  • Run for longer durations

Examples include:


  • Time-driven triggers

  • Form submission triggers

  • Sheet edit triggers

Creating Time-Based Triggers


Time-based triggers execute scripts at predefined intervals. You can schedule them to run:


  • Every minute, hour, or day

  • At a specific date and time

  • On a recurring weekly or monthly basis

Example: Running a Function Every Day at Midnight


function createTimeTrigger() {
  ScriptApp.newTrigger("myFunction")
    .timeBased()
    .everyDays(1)
    .atHour(0)
    .create();
}

function myFunction() {
  Logger.log("Daily task executed");
}

Steps to Set Up a Time-Based Trigger:


  • Open Google Apps Script

  • Click Triggers (clock icon) in the left panel

  • Click + Add Trigger

  • Select the function, execution time, and frequency

  • Click Save

Time based trigger

Event-Driven Triggers for Sheets, Forms, and Docs


Triggers for Google Sheets


  • onEdit(e): Runs when a user edits a cell.

  • onChange(e): Runs when structure changes (inserting rows, deleting columns).

Example: Send an Email When a Sheet is Edited


function onEdit(e) {
MailApp.sendEmail("[email protected]", "Sheet Edited", "A change was made in the sheet.");
}

Triggers for Google Forms


  • onFormSubmit(e): Runs when a user submits a form.

Example: Auto-Reply to Form Submission


function autoReply(e) {
var response = e.values;
var email = response[1]; // Assuming email is in the second column
MailApp.sendEmail(email, "Thank You!", "We received your response.");
}

Triggers for Google Docs


  • onOpen(e): Runs when a document is opened.

Example: Auto-Insert Header on Open


function onOpen() {
var doc = DocumentApp.getActiveDocument();
var body = doc.getBody();
body.insertParagraph(0, "This document is auto-managed.");
}

Best Methods for Managing Triggers


  1. Use Logging for Debugging: Incorporate Logger.log("Message") to monitor whether the script is executed.

  2. Avoid Too Many Triggers: Excessively using the trigger can hamper the performance.

  3. Test Before Deploying: Before applying the trigger execute your script manually to ensure the functionality.

  4. Use Installable Triggers for Advanced Tasks: If your script need to use emails or external services, always use installable triggers.

  5. Monitor Trigger Failures: Monitor execution logs in Apps Script Dashboard to fix the issues.

Final Thought


In Google Apps script triggers are used to automate the recursive tasks so that efficiency can be increased. Two types of triggers are being used in the Google Apps script. Simple triggers and installable triggers. Simple triggers are user friendly but it has some restrictions, while using installable triggers provides more adaptability and control. In the installable triggers, you can apply time-based triggers or event-driven triggers depending on the requirement.


By applying these triggers you can improve the performance of teams and manage the workflow in Google Workspace.