Log users visiting a Google Spreadsheet

I'm trying to track visitors from my organization to my Spreadsheet. I've been researching scripts that can do this and I finally seem to have one that allows to track edits. However, some of the people visiting my spreadsheet, won't make any edit. And I still want to retrieve their email address (or at least handle).

Seems like it would be a very simple script but I haven't found anything. Anyone know how we can do this?

Playing around, I found the solution. Here's the script:

function onOpen(e)
{ 
  try
  {
    var ui = SpreadsheetApp.getUi();
    ui.createMenu('Action')
    .addItem('Add Data', 'addData')
    .addToUi()  

    var sheet =SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Login Details");
    sheet.appendRow([Session.getActiveUser().getEmail(),new Date()]);

  }
  catch(e)
  {
    Logger.log(e);
  }
}