Script - Add a row beneath, based on conditional criteria - google-apps-script

Question

Dear Oracles of the script,
I have been trying to get some script to automatically add a row beneath the one I have inputted on, but only if the Balance is anything BUT zero. If it's zero, I don't want another row adding.
I've tried a few scripts and looked around the site, and tried them with triggers with on edit, but they just seem to add a row, despite me trying to state a condition for them to trigger.
function onEdit(event) {
var eventRange = event.range;
if (eventRange.getColumn() == 12) { // 12 = column of input that triggers it
var columnXRange =
SpreadsheetApp.getActiveSheet().getRange(eventRange.getRow(), 13,
eventRange.getNumRows(), 12); /// column number it affects
var values = columnXRange.getValues();
for (var i = 0; i < values.length; i++) {
if (!values[i][0]) { // If cell isn't empty
values[i][0] = '0';
}
}
columnXRange.setValues(values);
}
}
function Clear(e){
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getSheetByName('AGL');
sheet.getRange('N4:N').clearContent();
}
function AddRow() {
var sheet = SpreadsheetApp.getActiveSheet();
if (sheet.getName() == "AGL") {
var activeCell = sheet.getActiveCell();
if (activeCell.getColumn() == 13) {
var Balance = sheet.getRange('N:N');
if (Balance != '0'); {
sheet.insertRowAfter(activeCell.getRow());
}
}
}
}
In column N, I have an array formula working out the balance of stock in, against stock out.
In column M, I have a script running that will add a 0 when something is put into column L. I also have a script that erases the output of the array formula, so they don't get tangled up with each other.
I would like, when editing a row, when I place a figure in column L or M, and if the balance in Column N is greater than 0, I would like a new row adding underneath. (If you can get it to add the values from A & B, that'd be a bonus, but not fussy.) If the balance is 0, I don't want a row adding.
Currently, I have mixed results with it just adding a row every time I edit column N.

Answer 1

Requirement:
Add a row when columns L or M are edited and the value in column N is greater than 0 (& if possible, add values from columns A & B to the new row).
Solution:
This is pretty much all you need for your script. I've added comments to explain what each part is doing so it should be pretty easy to follow.
function onEdit(e) {
//define edited sheet, row number and column number
var sh = e.source.getActiveSheet();
var row = e.range.getRow();
var col = e.range.getColumn();
//get value of column N for edited row
var val = sh.getRange(row, 14).getValue();
//if columns L or M are edited and column N is greater than 0
if ((col === 12 || col === 13) === true && val > 0) {
//insert row below edited row
sh.insertRowAfter(row);
//get values of columns A and B of edited row
var vals = sh.getRange(row, 1, 1, 2).getValues();
//set values in columns A and B
sh.getRange(row+1, 1, 1, 2).setValues(vals);
}
}
Notes:
I haven't included any of your other functions, only adding a row, you can incorporate these in this function if you desire.
You won't be able to run this script manually at all (it'll fail on the first line), it'll just run automatically when the sheet is edited.
References:
Event Objects
Class Sheet