Use script to update column but only to last row - google-apps-script

Question

I am trying to have a script run that will basically find the row id in my spreadsheet then copy and paste that ID as a value instead of the formula. My solution feels clunky and I've run into a couple of issues.
The main issue is that I only want the script to update active rows (ie rows that have content in them), which is variable. This sheet is updated constantly throughout the day, and I really only want it to find and write the row id once per day (basically, these are tasks to be handed out and the row id sets priority). My plan is once I get the find row id/paste value scripts going, I'll use a trigger to run daily.
I'm a bb when it comes to coding and understanding scripts, so maybe explain it to me like im 5 if you can.
function getRowId(){
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheets()[0];
var cell = sheet.getRange("I2:I");
cell.setFormula("=row()");
}
function pasteValue(){
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sourceSheet = ss.getSheetByName("Sheet1");
var sheet = ss.getSheets();
var range = sourceSheet.getRange("I2:I");
range.setValues(range.getValues());
}

Answer 1

You can do the whole process in just one function. Here is the code I tested and worked successfully pasting the correlated row number in the "I" column of each row.
function pasteValue(){
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sourceSheet = ss.getSheetByName("Sheet1");
var range = sourceSheet.getDataRange().getValues();
for(var i=0; i<(range.length - 1); i++) {
var cell = sourceSheet.getRange(2 + i, 9);
cell.setValue(2 + i);
}
}
This code will do it only for the range of rows where is data already present, because it's using the getDataRange() function to make it more efficient. If you want to set the row number for all the rows present (even if they don't have any data), you need to change the declaration of the "range" variable to this:
var range = sourceSheet.getRange("I2:I");