A script that writes to the active tab can target the wrong place when its execution context changes. Use explicit target validation before any operational write.
Record file and tab identity separately
The spreadsheet file ID identifies the workbook. A sheet ID identifies a tab within that workbook and is independent of the tab’s current position. A tab title is useful context but can be renamed.
Do not assume the first item returned by a sheet list remains the business tab after someone rearranges tabs. Likewise, an active sheet depends on context and is not a durable destination policy.
Validate the destination before writing
Open the intended file explicitly where appropriate, identify the required tab, and check its ID, expected headers, and permitted output range. Stop if any identity or schema check fails.
Do not silently create a new tab when the expected one is missing unless that is a reviewed requirement. Automatic fallback can conceal a misspelled name or an incorrect workbook ID.
Use a controlled test and readback
First log only safe destination metadata or a dry-run change description. Then write a harmless sample to an approved test copy and read it back from the same explicit target.
Inspect how the script behaves under its actual manual or trigger execution identity. Preserve existing formulas and restrict the write to the authorized cells. Keep a checkpoint or backup for the exact changed range before live use. A completed execution status does not prove the correct tab received the data; destination identity and readback are separate parts of verification.
References
- Class SpreadsheetApp | Apps Script | Google for Developers
- Class Sheet | Apps Script | Google for Developers
- Installable Triggers | Apps Script | Google for Developers
Reviewed against the linked official product guidance on November 3, 2026. Features, limits, screen labels, and access can vary by account, platform, region, and organization policy.