I am trying to figure out the official code sample of Google:
/**
 * The event handler triggered when the selection changes in the spreadsheet.
 * @param {Event} e The onSelectionChange event.
 */
function onSelectionChange(e) {
  // Set background to red if a single empty cell is selected.
  var range = e.range;
  if(range.getNumRows() === 1 
      && range.getNumColumns() === 1 
      && range.getCell(1, 1).getValue() === "") {
    range.setBackground("red");
  }
}
but I got the error message:
TypeError: Cannot read property 'range' of undefined...
Can somebody give me a hint? It is my first attempt with Google Apps Script.
 
     
    