Ajax support for chosen

ajax-chosen.js

new function($) {
  return $.fn.ajaxChosen = function(options, callback) {
    var select = this,
        chosen;

    select.chosen();
    chosen = select.data('chosen');

    var val,
        timeout = null,
        delay = options.searchDelay || 500,
        success = options.success || null,
        input = select.next('.chzn-container').find(".search-field > input").length ?
          select.next('.chzn-container').find(".search-field > input") :
            select.next('.chzn-container').find(".chzn-search > input");

    options.beforeSend = function(xhr) {
      xhr.setRequestHeader("Accept", "application/json");
    };

    options.success = function(data) {
      if (data === null) return;

      var selected_items = [];

      select.find("option").each(function() {
        if (!$(this).is(":selected")) {
          return $(this).remove();
        } else {
          selected_items.push({ id: this.value, label: this.text});
        }
      });

      var items;

      if (typeof callback == "function") {
        items = callback(data);
      } else {
        items = data;
      }

      $(items).each(function() {
        var item = this;

        if (!$(selected_items).filter(function() { return this.id == item.id }).length) {
          $("<option />").attr('value', item.id).html(item.label).appendTo(select);
        }
      });

      select.trigger("liszt:updated");
      input.attr('value', val);
      input.css({ width: "auto" });

      if (typeof success == "function") return success();
    };

    input.bind("focus", function() {
      if (!select.find("option").filter(function() { return !$(this).is(":selected") }).length) {
        select.
          next('.chzn-container').
          find('.chzn-results').
          html('<li class="no-results">Start Typing</li>');
      }
    });

    input.bind("keyup", function() {
      val = $.trim($(this).attr('value'));

      if (val === $(this).data('prevVal')) return false;
      if (timeout) clearTimeout(timeout);

      select.
        next('.chzn-container').
        find('.no-results').
        text(val.length < 2 ? "Keep typing..." : "Looking for \"" + val + "\"");

      if (val.length < 2) return;

      $(this).data('prevVal', val);

      timeout = setTimeout(function() {
        options.data = { query: val };
        $.ajax(options);
      }, delay);
    });
  };
} (jQuery);