Log changes to a google spreadsheet (changelog sheet)

Changelog.gs

function onEdit() {
  // This script records changes to the spreadsheet on a "Changelog" sheet.
  // The changelog includes these columns:
  // "Timestamp", "Sheet name", "Cell address", "Column label", "Row label", "Value entered"
  // Version 1.1, written by --Hyde, 30 July 2014
  // See https://productforums.google.com/d/topic/docs/7CaJ_nYfLnM/discussion
  
  // edit the following lines to suit your needs
  // changes are only recorded from sheets listed below
  // escape regular expression metacharacters as in \. \$ \+ \* \? \( \) \[ \]
  // see http://en.wikipedia.org/wiki/Regular_expression
  // use '.+' to include all sheets
  var sheetsToWatch = ['outcome overview', 'Sheet1', 'Another sheet'];
  // name of the sheet where the changelog is stored
  var changelogSheetName = "Changelog";
  
  var timestamp = new Date();
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getActiveSheet();
  var cell = sheet.getActiveCell();
  var sheetName = sheet.getName();
  
  // if it is the changelog sheet that is being edited, do not record the change
  if (sheetName == changelogSheetName) return;
  
  // if the sheet name does not appear in sheetsToWatch, do not record the change
  var matchFound = false;
  for (var i = 0; i < sheetsToWatch.length; i++) {
    if (sheetName.match(sheetsToWatch[i])) matchFound = true;
  }
  if (!matchFound) return;
  
  var columnLabel = sheet.getRange(/* row 1 */ 1, cell.getColumn()).getValue();
  var rowLabel = sheet.getRange(cell.getRow(), /* column A */ 1).getValue();
  
  var changelogSheet = ss.getSheetByName(changelogSheetName);
  if (!changelogSheet) {
    // no changelog sheet found, create it as the last sheet in the spreadsheet
    changelogSheet = ss.insertSheet(changelogSheetName, ss.getNumSheets());
    // Utilities.sleep(2000); // give time for the new sheet to render before going back
    // ss.setActiveSheet(sheet);
    changelogSheet.appendRow(["Timestamp", "Sheet name", "Cell address", "Column label", "Row label", "Value entered"]);
    changelogSheet.setFrozenRows(1);
  }
  changelogSheet.appendRow([timestamp, sheetName, cell.getA1Notation(), columnLabel, rowLabel, cell.getValue()]);
}