Funkcja extend rozszerza lub nadpisuje domyślne opcje wtyczki.

jQuery.fn.foo = function(options) {
  var defaults = {
    length: 300,
    index: 2,
    text: "more"
  };
  var options = $.extend(defaults, options);
  var txt = "length: " + options['length'] + "\n";
  txt += "index: " + options['index'] + "\n";
  txt += "text: " + options['text'] + "\n";
  txt += "other: " + options['other'];
  alert(txt);
};