Range selection and copying fixed value (from a cell) in that selection - google-apps-script

Question

Background
I have some code which is supposed to copy certain rows from Sheet B into Sheet A based on integer values in cells E1,J1 and I1. E1 has date format. After rows are copied from Sheet B to A, I need to fill column 12 (Column L) with the date from E1 to newly added rows.
https://docs.google.com/spreadsheets/d/15pTVfcoxM2wQTMC-3iLzXVXIEEaZFYXaOf97amy4yRg/edit?usp=sharing
Problem
The last three rows of code is not working well. Even though I am trying to select range for same column 12 (column L), it seems to select multiple columns and an additional 2 rows than what I had expected.
function test() {
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("B");
var aa = sheet.getRange("E1");
var Date = aa.getValue();
var aa = sheet.getRange("J1");
var lastrow = aa.getValue();
var aa = sheet.getRange("I1");
var lastrowV = aa.getValue();
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("A");
var range = sheet.getRange(2, 1, lastrowV, 11);
var data = range.getValues();
sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("B");
sheet.getRange(lastrow, 1, data.length, 11).setValues(data); /* cell J1 gets updated after this*/
var aa = sheet.getRange("J1");
var lastrowN = aa.getValue() - 1;
range = sheet.getRange(lastrow, 12, lastrowN, 12);
range.activate();
sheet.getRange(lastrow, 12, lastrowN, 12).setValues(Date);
}

Answer 1

Background
The OP is attempting to insert a given date in the cell at the end of a row. However, the OP's definition of the range is faulty because it is selecting multiple columns (when only one column is required) and the number of rows is greater (by 2 (two)) than the number required. In addition, regardless of the range height, the OP is attempting to set a single value (rather than an array) into the range.
Problems
1) The definition of the datecolumn (Column L) included a value for the number of columns (probably a carry over from having defined the data range earlier).
Old range: getRange(lastrow,12, lastrowN, 12);. Delete the last parameter (number of columns) and the code behaves.
2) The code used this method setValues(Date) to populate the date column (8 rows in the OP's example data). the problem here is that the value assigned is the single value Date. not an array. This was addressed by creating and populating a temporary array datearray, and using this to update values in the date column.
3) In addition to the problems noted, the OP code is problematic in that a number of variables names were re-used with entirely different contexts (including "sheet" and "aa"), and some variables were declared multiple times. This made the code hard to read and debug. I took the opportunity to resolve as many of these as possible.
function so5473808801() {
// setup spreadsheet and sheets
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheetB = ss.getSheetByName("B");
var sheetA = ss.getSheetByName("A");
// define key variables
// date
var daterange = sheetB.getRange("E1");
var datevalue = daterange.getValue();
// rows on SheetA
var Arows = sheetB.getRange("I1"); // = 9
var Alastrow = Arows.getValue();
// rows on sheet B
var Brows = sheetB.getRange("J1"); // = 3
var Blastrow = Brows.getValue();
// define the data range on Sheet A
var Adatarange = sheetA.getRange(2, 1, Alastrow, 11);
// Logger.log("DEBUG: The defined range on Sheet A is "+Adatarange.getA1Notation());//DEBUG
var Adatavals = Adatarange.getValues();
// define a target range on Sheet B and set values from A
var targetrange = sheetB.getRange(Blastrow, 1, Adatavals.length, 11);
// Logger.log("DEBUG: The target on sheetB = "+targetrange.getA1Notation()); // DEBUG
targetrange.setValues(Adatavals);
// set a range to update date on Sheet B
var daterows = (Alastrow - 1); // doesn't take 2 row header on B intoi account
var Bdaterange = sheetB.getRange(Blastrow, 12, daterows);
// Logger.log("DEBUG: The date range on sheet B = "+Bdaterange.getA1Notation());
// create an array to store multiple copies of datevalue
var datearray = [];
//populate the array
for (var i = 0; i < daterows; i++) {
datearray.push([datevalue]);
}
// set the date into Column L
Bdaterange.setValues(datearray);
}