Google Sheets, Google Apps Script: onEdit
You’ve probably come across the problem where you need to know when a piece of data has been added to your spreadsheet. You probably have been equally frustrated that there is no out-of-the-box function that will do just this.
You’ve tried TODAY() and NOW(), but they change dynamically. What you really need here is something that does not change.
Let’s look at two workarounds that can help you out with this problem.