Why Google Apps Script Requires Functions: Understanding Its Execution Model

[Splendid Digital Solutions]

Disclaimer: This article was created with the assistance of an AI language model and is intended for informational purposes only. Please verify any technical details before implementation

Yes, in Google Apps Script (GAS), everything must be inside a function because:

1️⃣ Apps Script Executes Functions, Not Standalone Code

Unlike a standard JavaScript environment (like Node.js or the browser console), Apps Script requires code to be wrapped in a function. When you run a script, you select a function to execute.

For example, this won’t work in Apps Script:

for (let i = 1; i <= 10; i++) {
Logger.log(`Square of ${i} is ${i * i}`);
}

You’ll get an error because Apps Script expects a function to call.

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2️⃣ Functions Allow Execution from Apps Script UI

Apps Script does not auto-run scripts; instead, you run functions manually from the editor. Wrapping code inside a function lets you:
– Click Run and choose which function to execute.
– Schedule functions using triggers.
– Call functions from Google Sheets, Docs, Forms, etc.

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3️⃣ Function Scope Helps Maintain Clean Code

All code inside a function runs only when called, preventing unintended execution. This is useful in automation tasks, Gmail scripts, Google Sheets scripts, etc.

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📌 Exception: Triggers Can Run Code Automatically

You can use triggers (like onOpen() or onEdit()) to run code automatically when certain events occur. Example:

function onOpen() {
Logger.log("The script runs when the document opens.");
}

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🔹 Conclusion

✅ Functions are mandatory in Apps Script for execution.
✅ Apps Script does not allow standalone code execution like regular JavaScript.
✅ Functions let you run scripts manually or trigger them based on events.

 

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