Google apps script: Creates a Date Stamp if a column is edited

* Creates a Date Stamp if a column is edited.

// The column you want to check if something is entered.
var COLUMNTOCHECK = 6;   //cot can track khi co su thay doi
// Where you want the date time stamp offset from the input location. [row, column]
var DATETIMELOCATION = [0,-4];   //cot se dien thoi gian thay doi
// Sheet you are working on
var SHEETNAME = ‘Inventory’       //ten sheet co su thay doi

function onEdit(e) {
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
//checks that we’re on the correct sheet.
if( sheet.getSheetName() == SHEETNAME ) {
var selectedCell = ss.getActiveCell();
//checks the column to ensure it is on the one we want to cause the date to appear.
if( selectedCell.getColumn() == COLUMNTOCHECK) {
var dateTimeCell = selectedCell.offset(DATETIMELOCATION[0],DATETIMELOCATION[1]);
dateTimeCell.setValue(new Date());