Cookbooks
Google Apps Script
Chapter 5. Good Coding Practices
Handling errors

Google Apps Script:
Handling errors

How to:

Google Apps Script, being based on JavaScript, allows us to use the traditional try-catch statement for error handling, along with finally if cleanup is required regardless of success or error.

function myFunction() {
  try {
    // Code that might throw an error
    var sheet = SpreadsheetApp.getActiveSheet();
    var data = sheet.getRange("A1").getValue();
    if (data === "") {
      throw new Error("Cell A1 is empty.");
    }
    Logger.log(data);
  } catch (e) {
    // Error handling code
    Logger.log("Error: " + e.message);
  } finally {
    // Cleanup code, executed whether an error occurred or not
    Logger.log("Function completed.");
  }
}

Sample output without error:

[Cell value]
Function completed.

Sample output with an error (assuming A1 is empty):

Error: Cell A1 is empty.
Function completed.

Google Apps Script also supports throwing custom errors using the Error object and catching specific error types if needed. However, the absence of advanced error categorization makes it essential to rely on error messages for specificity.

Deep Dive

Historically, error handling in scripting languages like JavaScript (and by extension, Google Apps Script) has been less sophisticated than in some compiled languages, which offer features such as detailed exception hierarchies and comprehensive debugging tools. Google Apps Script’s model is relatively straightforward, leveraging JavaScript’s try-catch-finally paradigm. This simplicity aligns with the language’s design to rapidly develop and deploy small-to-medium scale applications within Google’s ecosystem, but it can sometimes limit developers dealing with complex error scenarios.

In more complex applications, programmers often supplement Google Apps Script’s native error handling with custom logging and error reporting mechanisms. This can include writing errors to a Google Sheet for audit or using third-party logging services through Google Apps Script’s URL Fetch Services to send error details out of the script environment.

Though Google Apps Script might lag behind languages like Java or C# in terms of built-in error handling complexity and capabilities, its integration with Google services and the simplicity of the try-catch-finally approach make it a powerful tool for developers to quickly automate tasks and create integrations within the Google ecosystem. Developers from other backgrounds may find the challenge lies not in mastering complex error handling patterns but in creatively leveraging what is available to ensure their scripts are robust and user-friendly.

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