Close or redirect tab window through using Google Apps script

I am trying to run a script that when a if() statement returns false it closes the current tab window of the google sheet or it redirects to another URL (as long as one of these work, thats ok for me).

I understand that this may be possible through using HTML but i don't know HTML well enough to do this.

I have found the below code which is meant to redirect to a different page which I tried but this does not work:

      return HtmlService.createHtmlOutput(
        "<form action='http://www.google.com' method='get' id='foo'></form>" + 
        "<script>document.getElementById('foo').submit();</script>");

Does anyone have any ideas?

See code that this is in below below:

  if (name == password)
  {
    Browser.msgBox('You have succesfully logged in');
    sortOutSheets();
  }
  else (name != password)
  {
    var response = Browser.msgBox('Login Failed - do you want to login again?', Browser.Buttons.YES_NO);
    if(response == "yes")
      enterPassword();
    else(response == "no")
    HtmlService.createHtmlOutputFromFile('Close Window');
  }
}

I have now turned to writing the HTML in another HTML file but still no luck