Adding a Pop-Up Message in Google Sheets Using Apps Script

function onEdit(e) {
  // Get the active spreadsheet and range
  const range = e.range;
  const sheet = e.source.getActiveSheet();

  // Check if the user has selected more than one cell
  if (range.getNumRows() > 1 || range.getNumColumns() > 1) {
    // Show a pop-up message
    SpreadsheetApp.getUi().alert("Please select a single cell to insert the date.");
    
    // Optional: Reset the range selection to a single cell
    range.getCell(1, 1).activate();
  } else {
    // Insert the current date if one cell is selected
    range.setValue(new Date());
  }
}