GreasemonkeyJavaScript Copy to Clipboard button

<SCRIPT LANGUAGE="JavaScript">
    <!-- Begin
    function copyit(theField) {
    var selectedText = document.selection;
    if (selectedText.type == 'Text') {
    var newRange = selectedText.createRange();
    theField.focus();
    theField.value = newRange.text;
    } else {
    alert('Alert: Select The text in the textarea then click on this button');
    }
    }
    // End -->
    </script>
    <input onclick="copyit(this.form.text_select)" type="button" value="Click Here to Copy the Highlighted Text" name="copy_button">

var tc = textToCopy.replace(/nn/g, 'n');
if (window.clipboardData) // IE
{
  window.clipboardData.setData("Text", tc);
}
else
{
  unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
  const clipboardHelper = Components.classes
      ["@mozilla.org/widget/clipboardhelper;1"].
      getService(Components.interfaces.nsIClipboardHelper);
  clipboardHelper.copyString(tc);
}