How to tell a script which row to start output - google-apps-script

Question

I am using a script to output the date and time that a row was last updated on a Google Sheet. It seems to work just fine, but I want it to only output beginning at the second row, since my first row is a header row full of labels for the columns. I can't seem to figure it out.
The script is from here: https://www.wikihow.com/Google-Sheets-How-to-Insert-Time-in-Cell-Automatically#Script-Editor
This is how it looks in my Apps Script:
/** #OnlyCurrentDoc */
function onEdit(e){
const sh = e.source.getActiveSheet();
sh.getRange ('A' + e.range.rowStart)
.setValue (new Date())
.setNumberFormat ('MM/dd/yyyy HH:MMam/pm');
}
I think I need to define rowStart, but I'm not sure how to do that and search engines haven't pulled up answers I understand.
I tried appending rowStart(2) and rowStart > 0 in place of the original rowStart, which produced errors and made the whole script stop working. I also tried the below with the same response.
rowStart(
value : 2
) : 2;
From here: https://help.grapecity.com/spread/SpreadJSWeb/JavascriptLibrary~GcSpread.Sheets.PrintInfo~rowStart.html
I am new to Google Apps Script (and any scripting), though a longtime Excel and Sheets user. So please explain it to me like I am five. 😅 Branching out!

Answer 1

OK, so this script, as it says on the original wikihow page, will:
insert a timestamp into the specified column any time you enter data into a cell, in the same row as the data you entered. For instance, if you type something into cell A2, a timestamp will appear in cell M2.
So essentially the way that script works, at least per my reading:
It is defining an onEdit handler which handles an edit event every time a user makes any change to any cell in the spreadsheet
the edit event (called e in the script) has a bunch of information about the edit on it, including the row number of the first row that was edited (e.range.rowStart)
the script contains a hard-coded column letter (in your case, A, in the example on wikihow they used M)
every time any edit is made , it goes to the cell identified by the hardcoded column letter and the 1st row that was edited, and it inserts the current date into that cell.
First of all, since this is JavaScript, you can paste your code into a text editor that supports JavaScript, like VSCode for example, and ask it to format it for you. This might bring some clarity to the code because the text editor knows what the syntax means, so it can give you some hints about whats going on or at very least it can make it look nicer:
/** #OnlyCurrentDoc */
function onEdit(e) {
const sh = e.source.getActiveSheet();
sh.getRange('A' + e.range.rowStart)
.setValue(new Date())
.setNumberFormat('MM/dd/yyyy HH:MMam/pm');
}
Second of all, single letter variable names and abbreviations are often frowned upon because they can prevent us from knowing what's going on. And sometimes code can be clarified by giving names to things that might otherwise not be obvious at all. So I will do some naming in this code:
/** #OnlyCurrentDoc */
function onEdit(editEvent) {
const sheet = editEvent.source.getActiveSheet();
const rowThatWasEdited = editEvent.range.rowStart;
const columnThatHoldsTheLastEditedDates = 'A';
const correspondingCell = columnThatHoldsTheLastEditedDates + rowThatWasEdited;
const rightNowDate = new Date();
sheet.getRange(correspondingCell)
.setValue(rightNowDate)
.setNumberFormat('MM/dd/yyyy HH:MMam/pm');
}
Finally, since this is javascript, we have access to all of the javascript features like if statements, loops, functions, etc. Since you want to make it ignore the header row, I would recommend an if statement: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else
if we are on the header row, do nothing. Otherwise, do the normal thing.
/** #OnlyCurrentDoc */
function onEdit(editEvent) {
const sheet = editEvent.source.getActiveSheet();
const rowThatWasEdited = editEvent.range.rowStart;
if(rowThatWasEdited > 1) {
const columnThatHoldsTheLastEditedDates = 'A';
const correspondingCell = columnThatHoldsTheLastEditedDates + rowThatWasEdited;
const rightNowDate = new Date();
sheet.getRange(correspondingCell)
.setValue(rightNowDate)
.setNumberFormat('MM/dd/yyyy HH:MMam/pm');
}
}