Print Listbox contents

function driverprint()
{
  var textboxText = document.getElementById('<%= TextBox1.ClientID %>');
  var ListBox1 = document.getElementById('<%= ListBox1.ClientID %>');
  var windowUrl = 'about:blank';
  var windowName = 'Print' + new
  Date().getTime();
  var printWindow = window.open(windowUrl, windowName, 'left=50000,top=50000,width=0,height=0');
  printWindow.document.write(textboxText.value);
  printWindow.document.write(ListBox1.value);

  printWindow.document.close();
  printWindow.focus();
  printWindow.print();
  printWindow.close();
}